Photonic system including micro ring modulator and method of using

A photonic system includes a waveguide. The photonic system further includes a micro ring modulator (MRM) spaced from the waveguide. The photonic system further includes a heater configured to increase a temperature of the MRM in response to the heater receiving a first voltage. The photonic system further includes a cooling element configured to decrease a temperature of the MRM in response to the cooling element receiving a second voltage.

BACKGROUND

Micro ring modulators (MRMs) are used in optical systems to couple optical signals into and out of waveguides in photonic systems. Semiconductor photonics, e.g., silicon photonics, is based on manipulating the thermo-optic effect exhibited by a semiconductor material. A material which exhibits a thermo-optic effect (TOE) changes refractive index in response to changes in temperature. MRMs are usable for filtering optical signals, coupling optical signals between optical waveguides, and other purposes in photonic systems. The MRM is located near an optical waveguide and is configured to optically couple with the optical waveguide to allow light of a specific wavelength to be coupled between the MRM and the optical waveguide. In some approaches, a heater is used to adjust a refractive index of the MRM in order to either enhance optical coupling between the MRM and the optical waveguide or reduce optical coupling between the MRM and the optical waveguide. The adjustment of the optical coupling allows the MRM to selectively perform functions, such as filtering, within a photonic system.

DETAILED DESCRIPTION

Micro ring modulators (MRMs) are usable to implement numerous functions within a photonic system, such as filtering and coupling. In order for an MRM to effectively implement the designed functionality within the photonic system, the MRM is in resonance with a wavelength of light. As photonic systems become more complex, a width of a waveband acceptable for coupling a desired signal wavelength becomes narrower due to an increased number of optical signals, each of having a distinct wavelength, propagating with the photonic system. Due to the high sensitivity of a refractive index of MRMs to manufacturing processes, MRMs often do not resonant with the designed signal wavelength or have low resonance with the desired signal wavelength.

In some approaches, a heater is used to change a temperature of the MRM in order to adjust the refractive index of the MRM in order to adjust the resonance with the desired wavelength. However, heaters are only able to adjust refractive index of the MRM in a single direction. That is, the refractive index of the MRM increases as the temperature increases. In a situation where the refractive index of the MRM is slightly above a target refractive index, the heater would heat the MRM to a next refractive index that is capable of resonating with the desired wavelength. MRM resonance for target wavelengths occurs at repeated wavelength periods, called the free spectral range (FSR). In some instances, the FSR is approximately 7 nanometers (nm). That is, for example, an MRM will resonate with green light at a wavelength of approximately 1306 nm and again at a wavelength of approximately 1313 nm. If the refractive index of the MRM following a manufacturing process is only slightly above a designed refractive index for resonating with a desired signal wavelength, the heater would be used to heat the MRM in order to target the next wavelength in the FSR for the desired signal wavelength.

In some instances, the MRM has a temperature coefficient of 0.07 nm/° C., meaning that the shift in the resonant wavelength for the MRM changes by 0.07 nm for each degree Celsius the MRM is heated. Assuming an FSR of approximately 7 nm, a heater would be used to heat the MRM by nearly 100° C. in some instances. This level of significant heating consumes a large amount of power for operating the MRM. As power consumption increases battery life decreases. Prolonging battery life is a significant goal of many devices, especially in portable devices such as mobile phones. Further, prolonged exposure to heating of nearly 100° C. eventually damages the MRM in some embodiments.

In order to help reduce power consumption and to reduce an amount of heating applied to an MRM, the current disclosure includes both a heating component and a cooling component. The cooling component is usable to adjust the refractive index of the MRM in an opposite manner from the heating component. Therefore, in a situation where the refractive index of the MRM is slight above a target refractive index due to manufacturing processes, the cooling component is able to lower the refractive index of the MRM to resonant with the desired signal wavelength. Being able to both lower and raise the refractive index of the MRM helps to reduce power consumption as well as prolonging the useful life of the MRM in comparison with photonic systems that include only the heating component.

FIG.1is a top view of a photonic system100including an MRM120in accordance with some embodiments. The photonic system100includes a waveguide110configured to carry at least one optical signal. The photonic system100further includes the MRM120located proximate to the waveguide110. The MRM120is configured to couple with the waveguide110to add an optical signal to the waveguide110or remove an optical signal from the waveguide110. The photonic system100further includes a heater130configured to raise a temperature of the MRM120. The heater130includes a first doped region132having a first dopant type; and a second doped region134having a second dopant type opposite the first dopant type. The heater130further includes a conductive element (shown inFIG.2), configured to supply a voltage to one of the first doped region132or the second doped region134to control a temperature of the MRM120. The photonic system100further includes a cooling element140configured to lower a temperature of the MRM120. The cooling element140includes a plurality of first doped regions142having the first dopant type; and a plurality of second doped regions144having the second dopant type. The cooling element140further includes a plurality of conductive elements146electrically connecting the first doped regions142and the second doped regions144. At least some of the plurality of conductive elements146extend over the MRM120. The cooling element140further includes a power source148for supplying power to the plurality of first doped regions142and the plurality of second doped regions144to control the temperature of the MRM120. The photonic system100is capable of both heating the MRM120and cooling the MRM120in order to facilitate optical coupling between the MRM120and the waveguide110. In comparison with other approaches that do not include both the heater130and the cooling element140, the photonic system100is able to reduce power consumption and increase useful life of the MRM120. The photonic system100further includes a controller150configured to control the heater130and the cooling element140in order to adjust a temperature of the MRM120.

The waveguide110includes a core including an optically transparent material and is configured to permit propagation of an optical signal along the waveguide110. In some embodiments, the core of the waveguide110includes silicon. In some embodiments, the core of the waveguide110includes polymer, glass, silicon nitride or another suitable material. A cladding material surrounds the core. The cladding material has a different refractive index from the core in order to help reduce an amount of signal loss as the optical signal propagates along the waveguide110. In some embodiments, the cladding has a lower refractive index than the core. In some embodiments, the cladding material is silicon oxide, polymer, or another suitable material. In some embodiments, the waveguide110has a circular cross-section. In some embodiments, the waveguide110has a rectangular cross-section, a triangular cross-section, or another suitable cross-sectional shape. In some embodiments, a width W2of the waveguide110ranges from about 0.01 μm to about 10 μm. If the width W2of the waveguide110is too small, a risk of optical signal loss due to an increased number of reflections during propagation increases, in some instances. If the width W2of the waveguide110is too large, an overall size of the photonic system100increases without an appreciable increase in performance, in some instances.

The MRM120is configured to selectively couple the optical signal into or out of the waveguide110. The MRM120is positioned close to, but not in contact with, the waveguide. A size of a spacing S1between the MRM120and the waveguide110determines the coupling efficiency between the MRM120and the waveguide110. In some embodiments, a spacing S1between the MRM120and the waveguide110ranges from about 0.01 microns (μm) to about 10 μm. If the spacing S1is too small a risk of unintentional leakage from the waveguide110into the MRM120increases, in some instances. If the spacing S1is too large coupling of the optical signal between the waveguide110and the MRM120is inefficient and a high signal loss results, in some instances. In addition to the spacing S1, optical properties, such as refractive index, also impact coupling efficiency. Light coupled from the waveguide110into the MRM120travels in a direction counter to a propagation direction of the optical signal in the waveguide110. The light intensifies due to constructive interference within the MRM120. The light is then able to be coupled from the MRM120into another waveguide, e.g., as inFIG.7, or into another optical component.

Materials and cross-sectional shape of the MRM120are similar to the waveguide110. In some embodiments, a core material of the MRM120is a same material as the core material for the waveguide110. In some embodiments, the core material of the MRM120is different from the core material of the waveguide110. In some embodiments, a cladding material of the MRM120is a same material as the cladding material for the waveguide110. In some embodiments, the cladding material of the MRM120is different from the cladding material of the waveguide110. In some embodiments, the cladding material of the MRM120is continuous with the cladding material the waveguide110.

In some embodiments, the MRM120is on a same plane, i.e., a same distance from a substrate, as the waveguide110. In some embodiments, the MRM120is closer to the substrate than the waveguide110. In some embodiments, the MRM120is farther from the substrate than the waveguide110. In some embodiments, the MRM120overlaps the waveguide110in a plan view. In situations where the MRM120is on a different plane from the waveguide110, the vertical separation is also included in determining the spacing S1.

In some embodiments, the MRM120is a ring structure. In some embodiments, the MRM120includes reflective gratings within to adjust a direction of propagation of light within the MRM120, e.g., to change counter-clockwise propagation to clockwise propagation. In some embodiments, a radius R1the MRM120ranges from about 1 μm to about 30 μm. If the radius R1of the MRM120is too small, signal loss increases as a result of a number of reflections as the optical signal propagates through the MRM120, in some instances. If the radius R1of the MRM120is too large, an overall size of the photonic system100increases without an appreciable increase in performance, in some instances.

In some embodiments, a width W1of the MRM120ranges from about 0.01 μm to about 10 μm. If the width W1of the MRM120is too small, signal loss within the MRM120due to increases reflections increases, in some instances. IF the width W1of the MRM120is too large, an overall size of the photonic system100increases without an appreciable increase in performance, in some instances. In some embodiments, the width W1of the MRM120is equal to the width W2of the waveguide110. In some embodiments, the width W1of the MRM120is different from the width W2of the waveguide110.

The heater130includes the first doped region132and the second doped region134proximate the MRM120. The heater130further includes a conductive element, e.g., as inFIG.2, configured to supply a voltage to the first doped region132or the second doped region134. Based on a resistance of a current flowing through the first doped region132and the second doped region134due to a voltage provided from the conductive element, heat is generated for raising a temperature of the MRM. In some embodiments, at least one of the first doped region132or the second doped region134is in direct contact with the MRM120. In some embodiments, at least one of the first doped region132or the second doped region134is spaced from the MRM120. In some embodiments, a dopant concentration of the first doped region132ranges from about 1e17dopants/cm3to about 1e19dopants/cm3. If the dopant concentration of the first doped region132is too large, then the resistance in the first doped region132does not generate sufficient heat for adjusting the temperature of the MRM120, in some instances. If the dopant concentration of the first doped region132is too small, then power consumption by the heater130increases, in some instances. In some embodiments, a dopant concentration of the second doped region134ranges from about 1e17dopants/cm3to about 1e19dopants/cm3. If the dopant concentration of the second doped region134is too large, then the resistance in the second doped region134does not generate sufficient heat for adjusting the temperature of the MRM120, in some instances. If the dopant concentration of the second doped region134is too small, then power consumption by the heater130increases, in some instances. In some embodiments, the dopant concentration of the first doped region132is equal to the dopant concentration of the second doped region134. In some embodiments, the dopant concentration of the first doped region132is different from the dopant concentration of the second doped region134.

The cooling element140includes the plurality of first doped regions142and the plurality of second doped regions144arranged in an alternating pattern of first doped regions142and second doped regions144. Each group of a first doped region142and a second doped region144is electrically connected in series with a next group of a first doped region142and a second doped region144. Further, a top thermal conductive plate (not shown) extends over a top of the plurality of first doped regions142and the plurality of second doped regions144; and a bottom thermal conductive plate (not show) extends below the plurality of first doped regions142and the plurality of second doped regions144. An electrical insulating material electrically insulates each of the top thermal conductive plate and the bottom thermal conductive plate from the plurality of first doped regions142and the plurality of second doped regions144. The electrical insulating material reduces a risk of short circuiting across the alternating first doped regions142and the second doped regions144in situations where at least one of the top thermal conductive plate or the bottom thermal conductive plate is also electrically conductive. In some embodiments, the top thermal conductive plate and the bottom thermal conductive plate independently include copper, tungsten, polymer, or another suitable thermally conductive material. In some embodiments, the electrical insulating material includes alumina, silicon oxide, silicon nitride, or another suitable electrically insulating material.

In operation, based on a direction of current through the plurality of first doped regions142and the plurality of second doped regions144, one of the top thermal conductive plate or the bottom thermal conductive plate will absorb heat, i.e., a cool side. The other of the top thermal conductive plate or the bottom thermal conductive plate will reject heat, i.e., a hot side. By passing the current through the plurality of first doped regions142and the plurality of second doped regions144in a specified direction, the cooling element140is able to reduce the temperature of the MRM120.

The cooling element140further includes conductive elements146which are used to electrically connect the alternating first doped regions142and second doped regions144. The conductive elements146are also cooled during operation of the cooling element140. As a result, the conductive elements146are also usable to absorb heat from the MRM120in order to reduce the temperature of the MRM120.

The cooling element140further includes a power source148configured to provide the current to the plurality of first doped regions142and the plurality of second doped regions144. In some embodiments, the power source148includes a battery of a device including the photonic system100; and the power supplied to the cooling element140is controlled by a switch, either analog or digital, between the battery and the cooling element140.

The controller150is configured to actively control the heater130and the cooling element140in order to adjust the temperature of the MRM120. Adjusting the temperature of the MRM120impacts coupling between the MRM120and the waveguide110.

In some embodiments, the controller is configured to receive information from one or more photodetectors (not shown) in order to determine whether the optical signal is being efficiently coupled between the waveguide110and the MRM120. In response to a determination that the optical signal is inefficiently coupled, the controller150controls either the cooling element140or the heater130to adjust the temperature of the MRM120to increase coupling. One of ordinary skill in the art would also understand that the temperature of the MRM120is controllable to selectively reduce coupling with the waveguide110based on a designed functionality of the photonic system100.

In addition to controlling coupling during operation, the controller150is also usable to tune the MRM120prior to normal operation. As noted above, the MRM120is sensitive to processing and optical properties of the MRM120are altered during processing subsequent to formation of the MRM120, in some instances. As a result, coupling between the components will be different than an initial design in some instances. The controller150is configured to control the heater130and the cooling element140in order to determine maximum and minimum coupling values by measuring efficiency of converting optical signals to electrical signals from the at least one photodetector. In some embodiments, the tuning is re-performed periodically to account for variations in the performance of the MRM120over time.

In comparison with other approaches, the photonic system100is able to control the temperature of the MRM120in both a heating direction and a cooling direction. The ability to control the temperature of the MRM120in both direction helps to adjust the refractive index of the MRM120to couple to an FSR of the target wavelength closest to the inherent refractive index of the MRM120following manufacturing processes. As discussed above, the MRM120is sensitive to the manufacturing processes. As a result, being able to tune the MRM120in both the heating direction and the cooling direction helps to reduce power consumption by the photonic system100in comparison with other approaches that only include one direction of tuning, e.g., heating. In addition, subjecting the MRM120to a lower temperature variation by being able to tune toward the closest FSR helps to prolong the useful life of the MRM120in comparison with other approaches that are only able to tune in a single direction.

FIG.2is a cross-sectional view of the photonic system100including the MRM120in accordance with some embodiments. The cross-sectional view ofFIG.2is taken along line A-A ofFIG.1. Similar elements inFIG.2have a same reference number as inFIG.1. The photonic system100includes the MRM120formed integrally with the first doped region132and the second doped region134. In some embodiments, the MRM120is spaced from at least one of the first doped region132or the second doped region134. A heater conductive element136is over the first doped region132and the second doped region134. The heater conductive element136is configured to provide a voltage to the first doped region132or the second doped region134in order to heat the MRM120. Additionally, resistance within the heater conductive element136is also able to provide additional heating to the MRM120in order to help minimize power consumption during heating of the MRM120. The conductive element146is over the heater conductive element136. As discussed above, the conductive element146is part of the cooling element140and is usable to cool the MRM120.

The photonic system100includes the heater conductive element136being closer to the MRM120than the conductive element146. In some embodiments, the conductive element146is closer to the MRM120than the heater conductive element136. For example, in some embodiments, a position of the heater conductive element136and a position of the conductive element146are reversed from the arrangement inFIG.2. In some embodiments, the conductive element146is on a same plane as the heater conductive element136. That is, both the conductive element146and the heater conductive element136are a same distance from the MRM120; and the conductive element146is offset from the heater conductive element136in a direction into the page forFIG.2. In some embodiments, a distance D1from the first doped region132to the heater conductive element136is less than 10 μm. In some embodiments, the heater conductive element136directly contacts the first doped region132or the second doped region134. If the heater conductive element136is too far from the first doped region132, then heating of the MRM120is inefficient and power consumption is increased in some instances. In some embodiments, a distance D2from the first doped region132to the conductive element146is less than 10 μm. In some embodiments, the conductive element146directly contacts the first doped region132or the second doped region134. If the conductive element146is too far from the first doped region132, then cooling of the MRM120is inefficient and power consumption is increased in some instances.

FIG.3is a cross-sectional view of the photonic system100including the MRM120in accordance with some embodiments. The cross-sectional view ofFIG.3is taken along line B-B ofFIG.1. Similar elements inFIG.3have a same reference number as inFIG.1. The photonic system100includes the first doped region142and the second doped region144. The first doped region142is spaced from the second doped region144by a width W3. In some embodiments, the width W3ranges from about 0.01 μm to about 10 μm. If the width W3is too large, then cooling efficiency of the cooling element140is reduced, in some embodiments. If the width W3is too small, then a risk of short circuiting between the first doped region142and the second doped region144increases, in some instances. In some embodiments, a space between adjacent first doped regions142and second doped regions144is uniform across the entire photonic system100. In some embodiments, at least one space between a first doped region142and an adjacent second doped region144is different from a space between another first doped region142and another adjacent second doped region144.

The first doped region142includes a semiconductor material310. In some embodiments, the semiconductor material310includes silicon. In some embodiments, the semiconductor material310includes poly silicon, a compound semiconductor material, or another type of semiconductor material. Within the semiconductor material310is a doped area315including dopants of the first dopant type. In some embodiments, a dopant concentration of the doped area315ranges from about 1e17dopants/cm3to about 1e19dopants/cm3. If the dopant concentration of the doped area315is too large, then the resistance in the first doped region142does not generate sufficient cooling for adjusting the temperature of the MRM120, in some instances. If the dopant concentration of the doped area315is too small, then power consumption by the cooling element140increases, in some instances. In some embodiments, a width W4of the first doped region142ranges from about 0.01 μm to about 10 μm. If the width W4is too large, then a size of the photonic system100is increased without appreciable improvement in performance, in some instances. If the width W4is too small, then a resistance within the first doped region142is increased and cooling efficiency is reduced, in some instances. In some embodiments, a height H of the first doped region142ranges from about 0.01 μm to about 10 μm. If the height H is too large, then a size of the photonic system100is increased without appreciable improvement in performance, in some instances. If the height H is too small, then a resistance within the first doped region142is increased and cooling efficiency is reduced, in some instances.

The second doped region144includes a semiconductor material320. In some embodiments, the semiconductor material320includes silicon. In some embodiments, the semiconductor material320includes poly silicon, a compound semiconductor material, or another type of semiconductor material. In some embodiments, the semiconductor material310is a same material as the semiconductor material320. In some embodiments, the semiconductor material310is different from the semiconductor material320. Within the semiconductor material320is a doped area325including dopants of the second dopant type. In some embodiments, a dopant concentration of the doped area325ranges from about 1e17dopants/cm3to about 1e19dopants/cm3. If the dopant concentration of the doped area325is too large, then the resistance in the second doped region144does not generate sufficient cooling for adjusting the temperature of the MRM120, in some instances. If the dopant concentration of the doped area325is too small, then power consumption by the cooling element140increases, in some instances. In some embodiments, a width W4of the second doped region144ranges from about 0.01 μm to about 10 μm. If the width W4is too large, then a size of the photonic system100is increased without appreciable improvement in performance, in some instances. If the width W4is too small, then a resistance within the second doped region144is increased and cooling efficiency is reduced, in some instances. In some embodiments, the width of the first doped region142is equal to the width of the second doped region144. In some embodiments, the first doped region142has a different width from the second doped region144. In some embodiments, a height H of the second doped region144ranges from about 0.01 μm to about 10 μm. If the height H is too large, then a size of the photonic system100is increased without appreciable improvement in performance, in some instances. If the height H is too small, then a resistance within the second doped region144is increased and cooling efficiency is reduced, in some instances. In some embodiments, the height of the first doped region142is equal to the height of the second doped region144. In some embodiments, the first doped region142has a different height from the second doped region144.

FIG.4is a cross-sectional view of the photonic system100including the MRM120in accordance with some embodiments. The cross-sectional view ofFIG.4is taken along line C-C ofFIG.1. Similar elements inFIG.4have a same reference number as inFIG.1andFIG.2. The photonic system100includes a substrate405supporting the MRM120and the waveguide110. The photonic system100further includes a first slab protrusion410separated from the MRM120by a first gap420. The photonic system100further includes a second slab protrusion430separated from the waveguide110by a second gap440. The substrate405is integral with the MRM120and the waveguide110. In some embodiments, the substrate405is separate from at least one of the waveguide110or the MRM120. The first slab protrusion410and the second slab protrusion430are the result of the manufacturing process and are not intended to function as part of the photonic system100. However, removal of the first slab protrusion410and the second slab protrusion430incurs additional processing time and cost. Additionally, the additional processing to remove the first slab protrusion410and the second slab protrusion430potentially impacts the performance of the MRM120.

In some embodiments, a width Wa of the first slab protrusion410is less than about 10 μm. If the width Wa is too large, then a size of the photonic device100is increased without significant difference in device performance, in some instances. In some embodiments, the first slab protrusion410is eliminated entirely, so the width Wa is zero. In some embodiments, a width Wc of the second slab protrusion430is less than about 10 μm. If the width Wc is too large, then a size of the photonic device100is increased without significant difference in device performance, in some instances. In some embodiments, the second slab protrusion430is eliminated entirely, so the width Wc is zero. In some embodiments, the width Wa is equal to the width Wc. In some embodiments, the width Wa is different from the width Wc. In some embodiments, a width Wb of the first gap420ranges from about 0.1 μm to about 10 μm. If the width Wb is too small, a risk of the optical signal coupling from the MRM120into the first slab protrusion410increases, in some instances. If the width Wb is too large, the size of the photonic system100increase without appreciable improvement in performance, in some instances. In some embodiments, where the first slab protrusion410is removed, the first gap420is also eliminated. In some embodiments, a width Wd of the second gap440ranges from about 0.1 μm to about 10 μm. If the width Wd is too small, a risk of the optical signal coupling from the waveguide110into the second slab protrusion430increases, in some instances. If the width Wd is too large, the size of the photonic system100increase without appreciable improvement in performance, in some instances. In some embodiments, where the second slab protrusion430is removed, the second gap440is also eliminated. In some embodiments, the width Wb is equal to the width Wd. In some embodiments, the width Wb is different from the width Wd.

In some embodiments, a height Ha of the MRM120from a bottom of the substrate405ranges from about 0.01 μm to about 10 μm. If the height Ha is too small, degradation of the optical signal within the MRM120is increased due to a larger number of reflections, in some instances. If the height Ha is too large, a size of the photonic system100is increased without appreciable improvement in performance in some instances. In some embodiments, a height Hb of the substrate405is less than about 10 μm. If the height Hb is too large, then a size of the photonic system100is increased without appreciable improvement in performance, in some instances. In some embodiments, the substrate405is removed entirely, e.g., by grinding or etching, and the height Hb is zero.

FIG.5is a cross-sectional view of the photonic system500including the MRM120in accordance with some embodiments. The cross-sectional view ofFIG.5is taken along line C-C ofFIG.1. Similar elements inFIG.5have a same reference number as inFIG.1andFIG.4. In comparison with the photonic system100inFIG.4, the photonic system500excludes the first slab protrusion410, the second slab protrusion430and the portions of the substrate405extending beyond the waveguide110and the MRM120. In some embodiments, the arrangement of photonic system500is called a slab-free arrangement. One of ordinary skill in the art would recognize that the slab-free arrangement is usable with respect to the photonic system100inFIGS.1-3.

In comparison with the photonic system100inFIG.4, the photonic system500includes additional processing operations to remove the first slab protrusion410, the second slab protrusion, and the portions of the substrate405beyond the waveguide110and the MRM120. However, the slab-free arrangement has improved process variation in comparison with the photonic system100inFIG.4. As a result, the MRM120is less likely to have a significantly difference from the designed refractive index; and tuning of the MRM120would require less heating or cooling. The reduced heating or cooling helps to reduce power consumption for a device including the photonic system500in comparison with the photonic system100inFIG.4.

FIG.6is a top view of a portion of a photonic system600including the MRM120, in accordance with some embodiments. The photonic system600is similar to the photonic system100(FIG.1); and similar elements having a same reference number. In comparison with the photonic system100(FIG.1), the photonic system600includes a curved waveguide610. Dimensions, material, and shape of the waveguide610are similar to the waveguide110(FIG.1); however, the waveguide610is curved instead of straight. The waveguide610has a radius R2. The radius R2is larger than the radius R1of the MRM120. In some embodiments, a radius R2the waveguide610ranges from about 1 μm to about 30 μm. If the radius R2of the waveguide610is too small, signal loss increases as a result of a number of reflections as the optical signal propagates through the curve of the waveguide610, in some instances. If the radius R2of the waveguide610is too large, an overall size of the photonic system600increases without an appreciable increase in performance, in some instances.

The photonic system600is useful for routing optical signals of a device between components that are not aligned. The use of the curved waveguide610permits the propagation between components which are offset in two dimensions instead of just one dimension, as in the photonic system100(FIG.1). One of ordinary skill in the art would understand that the photonic system600is able to be implemented in both the slab-free arrangement and an arrangement including slab components; and that the description details inFIGS.1-5are applicable to the photonic system600. One of ordinary skill in the art would recognize that while the photonic system600inFIG.6includes the waveguide610curving in a same direction as the MRM120, a waveguide610that curves in an opposite direction from the MRM120is also within the scope of this description.

FIG.7is a top view of a portion of a photonic system700including the MRM120, in accordance with some embodiments. The photonic system700is similar to the photonic system100(FIG.1); and similar elements having a same reference number. In comparison with the photonic system100(FIG.1), the photonic system700includes a waveguide710on an opposite side of the MRM120from the waveguide110. Further, in comparison with the photonic system100(FIG.1), the photonic system700includes a heater730different from the heater130(FIG.1). Dimensions, material, and shape of the waveguide710are similar to the waveguide110(FIG.1).

The heater730includes a first doped region pair735adiscontinuous with a second doped region pair735b, instead of the single continuous doped region pair of the photonic system100(FIG.1). The first doped region pair735aincludes a first doped region732ahaving the first dopant type; and a second doped region734ahaving the second dopant type. The second doped region pair735bincludes a first doped region732bhaving the first dopant type; and a second doped region734bhaving the second dopant type. Each of the first doped regions732aand732bhave a similar shape and doping concentration as the first doped region132(FIG.1) except the first doped regions732aand732bextend over less of the MRM120than the first doped region132(FIG.1). Similarly, each of the second doped regions734aand734bhave a similar shape and doping concentration as the second doped region134(FIG.1) except the second doped regions734aand734bextend over less of the MRM120than the second doped region134(FIG.1). Due to the discontinuity between the first doped region pair735aand the second doped region pair735b, the MRM120is capable of coupling with both the waveguide110and the waveguide710. This increased functionality permits the photonic system700to transfer optical signals between the waveguide110and the waveguide710using the MRM120.

The waveguide710includes a core including an optically transparent material and is configured to permit propagation of an optical signal along the waveguide710. In some embodiments, the core of the waveguide710includes silicon. In some embodiments, the core of the waveguide710includes polymer, glass, silicon nitride or another suitable material. In some embodiments, the core of waveguide710includes a same material as the core of the waveguide110and the MRM120. In some embodiments, the core of the waveguide710includes a different material from at least one of the core of the waveguide110or the MRM120. A cladding material surrounds the core. The cladding material has a different refractive index from the core in order to help reduce an amount of signal loss as the optical signal propagates along the waveguide710. In some embodiments, the cladding has a lower refractive index than the core. In some embodiments, the cladding material is silicon oxide, polymer, or another suitable material. In some embodiments, the cladding of waveguide710includes a same material as the core of the waveguide110and the MRM120. In some embodiments, the cladding of the waveguide710includes a different material from at least one of the core of the waveguide110or the MRM120. In some embodiments, the waveguide710has a circular cross-section. In some embodiments, the waveguide710has a rectangular cross-section, a triangular cross-section, or another suitable cross-sectional shape. In some embodiments, a cross-sectional shape of waveguide710is a same shape as the waveguide110and the MRM120. In some embodiments, the cross-sectional shape of the waveguide710is different from at least one of the waveguide110or the MRM120. In some embodiments, a width W5of the waveguide710ranges from about 0.01 μm to about 10 μm. If the width W5of the waveguide710is too small, a risk of optical signal loss due to an increased number of reflections during propagation increases, in some instances. If the width W5of the waveguide750is too large, an overall size of the photonic system700increases without an appreciable increase in performance, in some instances.

The MRM120is positioned close to, but not in contact with, the waveguide710. A size of a spacing S2between the MRM120and the waveguide710determines the coupling efficiency between the MRM120and the waveguide710. In some embodiments, a spacing S2between the MRM120and the waveguide710ranges from about 0.01 μm to about 10 μm. If the spacing S2is too small a risk of unintentional leakage from the waveguide710into the MRM120increases, in some instances. If the spacing S2is too large coupling of the optical signal between the waveguide710and the MRM120is inefficient and a high signal loss results, in some instances. In addition to the spacing S2, optical properties, such as refractive index, also impact coupling efficiency. Light coupled from the waveguide710into the MRM120travels in a direction counter to a propagation direction of the optical signal in the waveguide710. The light intensifies due to constructive interference within the MRM120, which helps to facilitate optical signal transfer between the waveguide710and the waveguide110.

The photonic system700is useful for routing optical signals of a device between components that are not aligned. The ability to couple optical signals between the waveguide110and the waveguide710allows communication between components which are offset in two dimensions instead of just one dimension, as in the photonic system100(FIG.1). One of ordinary skill in the art would understand that the photonic system700is able to be implemented in both the slab-free arrangement and an arrangement including slab components; and that the description details inFIGS.1-5are applicable to the photonic system700. One of ordinary skill in the art would also understand that while the photonic system700includes straight waveguides110and710, in some embodiments, at least one of the waveguides in the photonic system700is curved, such as curved waveguide610(FIG.6).

FIG.8is a top view of a portion of a photonic system800including the MRM120, in accordance with some embodiments. The photonic system800is similar to the photonic system100(FIG.2), i.e., the cross-sectional view is taken along the line A-A in a photonic system similar to the photonic system100(FIG.1); and similar elements having a same reference number. In comparison with the photonic system100(FIG.2), the photonic system800includes a substrate810and a heater conductive element836on an opposite side of the substrate810from the MRM120. Further, in comparison with the photonic system100(FIG.2), the photonic system800includes different doping regions, as described below. In some embodiments, the photonic system800includes a thermal via840extending through the substrate to provide conductive heat transfer between the heater conductive element836and the MRM120.

In some embodiments, the substrate810between the heater conductive element836and the MRM120is continuous with no openings or gaps. In some embodiments, the thermal via840is also electrically conductive and provides an electrical signal between the heater conductive element836and the doped region834b. While a single thermal via840is included inFIG.8, one of ordinary skill in the art would understand that multiple thermal vias840are within the scope of this description. In some embodiments, the photonic system800further includes an opening850in the substrate810to facilitate heat transfer between the heater conductive element836and the MRM120. While a single opening850is included inFIG.8, one of ordinary skill in the art would understand that multiple openings850are within the scope of this description. While the photonic system800inFIG.8includes both a thermal via840and an opening850, one of ordinary skill in the art would understand that a photonic system including only one or more thermal vias840without any openings850; and a photonic system including only one or more openings850without any thermal vias840are also within the scope of this description.

In some embodiments, the heater conductive element836is in direct contact with the substrate810on the opposite side from the MRM120. In some embodiments, the heater conductive element836is spaced from the substrate810on the opposite side from the MRM120.

In order to help facilitate the change in location of heater conductive element836on the opposite side of the substrate810from the MRM120, positions of doped regions832a-cand834a-care adjusted in comparison with the photonic device100(FIG.2). Each of the doped regions832a-chave the first dopant type and have dopant concentrations similar to those described above with respect to the first doped region132. In some embodiments, each of the doped regions832a-chave a same dopant concentration. In some embodiments, at least one of the doped regions832a-chas a different dopant concentration from at least one other of the doped regions832a-c. Each of the doped regions834a-chave the second dopant type and have dopant concentrations similar to those described above with respect to the second doped region134. In some embodiments, each of the doped regions834a-chave a same dopant concentration. In some embodiments, at least one of the doped regions834a-chas a different dopant concentration from at least one other of the doped regions834a-c. The doped region832aand the doped region834aare usable to provide electrical connection to the conductive element146. The doped region832cand the doped region834care usable as doped regions within the MRM120. The doped region832band the doped region834bare usable as doped regions for heating the MRM120, similar to the first doped region132and the second doped region134(FIG.2).

The thermal via840is configured to provide a path for heat generated by the heater conductive element836to increase a temperature of the MRM120. In some embodiments, the thermal via840includes copper, tungsten, polymer, or another suitable thermally conductive material. In some embodiments, the thermal via840further includes a liner between the substrate810and the thermally conductive material to help minimize diffusion of the thermally conductive material into the substrate810. In some embodiments, the liner includes silicon oxide, silicon nitride, or another suitable liner material. In some embodiments, the thermal via840is also electrically conductive and is usable to provide a voltage to the doped region834bfor heating the MRM120. In some embodiments, the thermal via840is formed by forming the MRM120on a first side of the substrate810; etching the substrate810to define a thermal via opening; depositing a thermally conductive material in the thermal via opening; and forming the heater conductive element836in contact with the thermally conductive material.

The opening850is configured to provide a path for heat generated by the heater conductive element836to increase the temperature of the MRM120. In some embodiments, the opening850is formed by forming the MRM120on a first side of the substrate810; etching the substrate810to define the opening850; and forming the heater conductive element836proximate the opening850. Heat transfer between the heater conductive element836and the MRM120is less efficient through the opening850than heat transfer using the thermal via840. However, the use of the opening850utilizes less processing operations and therefore reduces a risk of additional impact on the MRM120performance.

The photonic system800is useful for reducing a size of the photonic system in comparison with the photonic system100(FIG.1) by placing some components of the photonic system800on an opposite side of the substrate810. One of ordinary skill in the art would understand that the photonic system800is able to be implemented in both the slab-free arrangement and an arrangement including slab components; and that the description details inFIGS.1-5are applicable to the photonic system800. One of ordinary skill in the art would also understand that while the photonic system800includes the conductive element146on a same side of the substrate810as the MRM120, a photonic system which includes the heater conductive element836on a same side of the substrate810as the MRM120; and the conductive element146on an opposite side of the substrate810from the MRM120is within the scope of this description.

FIG.9is a flowchart of a method900of using a photonic system in accordance with some embodiments. The method900is capable of being implemented using any of the photonic system100(FIGS.1-4); the photonic system500(FIG.5); the photonic system600(FIG.6); the photonic system700(FIG.7); the photonic system800(FIG.8); or another suitable photonic system. The method900is usable for tuning of an MRM to couple with a waveguide.

In operation905, a coupling efficiency between an MRM and a waveguide is detected. In some embodiments, the coupling efficiency is determined based on analysis of an optical signal received by a photodetector (PD). The PD detects one or more wavelengths and an intensity of each wavelength of the optical signal. The detected wavelengths and intensity are compared with design targets to determine how efficiently the optical signal propagated through the photonic system including the MRM. For example, in some embodiments where the MRM is configured to remove a specific wavelength from the optical signal, if the PD receives a high intensity of light of that wavelength from the waveguide, the coupling efficiency is determined to be low. In contrast, in some embodiments where the MRM is configured to insert a specific wavelength into the waveguide and the PD receives a high intensity of that waveguide from the waveguide, the coupling efficiency is determined to be high.

In operation910, the detected coupling efficiency is compared with design specification to determine whether the detected coupling efficiency meets the design specifications. In some embodiments, the comparison is performed using a processor connected to a non-transitory computer readable medium configured to store the design specifications as well as the information used to determine coupling efficiency. In some embodiments, a threshold buffer with respect to the design specifications is used to determine whether the detected coupling efficiency satisfies the design specification. In some embodiments, the threshold buffer is predetermined by a photonic system designer. In response to a determination that the coupling efficiency meets the design specifications, the method900proceeds to optional operation920, i.e., Yes inFIG.9. In response to a determination that the coupling efficiency fails to meet the design specifications, the method900proceeds to operation915, i.e., No inFIG.9.

In operation915, the temperature of the MRM is adjusted using a heater or a cooling element. In some embodiments, the heater corresponds to the heater130(FIG.1), the heater730(FIG.7), or another suitable heater. In some embodiments, the cooling element corresponds to the cooling element140(FIG.1), or another suitable cooling element. In some embodiments, a processor, such as the processor used to determine the coupling efficiency, is usable to determine whether to use the heater or the cooling element. In some embodiments, the processor is part of the controller150(FIG.1). In some embodiments, the processor relies on empirical data, e.g., stored in the non-transitory computer readable medium, from previously manufacturing photonic systems to determine whether the temperature of the MRM should be increased or decreased. In some embodiments, the processor is configured to activate one of the heater or the cooling element up to a predetermined temperature adjustment threshold to determine whether the coupling efficiency is able to be adjusted to satisfy the design specifications. Once the predetermined temperature adjustment threshold is reached, the process stops activating the previous one of the heater or the cooling element and begins activating the other of the heater or cooling element to attempt to adjust the coupling efficiency to meet the design specifications. In some embodiments, the predetermined temperature adjustment threshold is set based on the FSR of the target wavelength. In some embodiments, the temperature adjustment threshold is set to a temperature adjustment corresponding to approximately half of the FSR. For example, in some embodiments, the FSR is 7 nm, so the temperature adjustment threshold would be set to the temperature adjustment to change the resonance of the MRM by 3.5 nm. Using an example temperature change relationship of 0.07 nm/° C., the temperature adjustment threshold would be 50° C., in some embodiments. One of ordinary skill in the art would recognize that this is merely an example calculation and that other values and criteria for the predetermined temperature adjustment threshold are within the scope of this description. Following operation915, the method900returns to operation905to determine a coupling efficiency with the MRM at the adjusted temperature.

In optional operation920, an operational time of the photonic system is monitored to determine whether a threshold operation time is reached. In response to a determination that the threshold operation time is reached, the method900returns to operation905, i.e., Yes inFIG.9. In response to a determination that the threshold operational time is not reached, the method900repeats optional operation920, i.e., No inFIG.9. In some embodiments, the threshold operation time is set based on empirical data for operation of other photonic systems. In some embodiments, the threshold operation time is set by a designer of the photonic system. In some embodiments, the operation920is omitted and the photonic system operates utilizing a same temperature for the MRM first determined to satisfy the design specifications. Omitting the operation920potentially reduces a useful life of the photonic system, but reduces processing load for a processor or controller, e.g., the controller150(FIG.1), of the photonic system.

In some embodiments, the method900includes additional operations. For example, in some embodiments, the method900includes detecting coupling efficiency between the MRM and another waveguide within the photonic system. In some embodiments, at least one operation of the method900is omitted. For example, in some embodiments, the optional operation920is omitted. In some embodiments, an order of operations of the method900is adjusted. For example, in some embodiments, an initial temperature of the MRM is set, based on empirical evidence from previously manufacturing photonic systems, using operation915prior to operation905in an attempt to minimize a number of iterations of the operations905-915. One of ordinary skill in the art would recognize that additional modifications to the method900are within the scope of this description.

FIGS.10A-10Hare cross-sectional views of a portion of a photonic system having an MRM at various stages of manufacture, in accordance with some embodiments.FIG.11is a flowchart of a method1100of making a photonic system having an MRM, in accordance with some embodiments. For the sake of clarity description of theFIGS.10A-10HandFIG.11are combined. However, one of ordinary skill in the art would understand that the structures inFIGS.10A-10Hare capable of being formed using methods other than method1100(FIG.11). Further, one of ordinary skill in the art would understand that the method1100is capable of forming structures other than those inFIGS.10A-10H.

FIG.10Ais a cross-sectional view of a portion of a photonic system1000A having an MRM following formation of a wafer, in accordance with some embodiments. The photonic system1000A includes a semiconductor layer1002, an insulating layer1004over the semiconductor layer1002, and a semiconductor layer1006over the insulating layer1004.

In some embodiments, the semiconductor layer1002includes silicon, silicon germanium, or another suitable semiconductor material. In some embodiments, the insulating layer1004includes silicon oxide, silicon nitride, silicon oxynitride, or another suitable insulating material. In some embodiments, the semiconductor layer1006includes silicon, silicon germanium, or another suitable semiconductor material. In some embodiments, the semiconductor layer1002includes a same material as the semiconductor layer1006. In some embodiments, the semiconductor layer1002include a different material from the semiconductor layer1006.

Turning toFIG.11, the method1100includes operation1105in which a wafer is etched to define ring structure and cooling structures. In some embodiments, the operation1105includes a single etching process. In some embodiments, the operation1105includes multiple etching processes. In some embodiments, the operation1105includes a wet etching process or a dry etching process. In some embodiments, the etching process further includes a photolithography process to define the locations where material is removed by the etching process.

FIG.10Bis a cross-sectional view of a portion of a photonic system1000B having an MRM following etching of the wafer, in accordance with some embodiments. The photonic system1000B is similar to the photonic system1000A (FIG.10A), and similar elements have a same reference number. In comparison with the photonic system1000A (FIG.10A), the photonic system1000B includes a plurality of first recesses1010and a plurality of second recesses1015.

The plurality of first recesses1010separate cooling structures from the ring structure. Each of the plurality of first recesses1010are deeper than each of the plurality of second recesses1015. Each of the plurality of first recesses1010extend through an entirety of the semiconductor layer1006. In some embodiments, at least one of the plurality of first recesses1010does not extend through an entirety of the semiconductor layer1006. In some embodiments, at least one of the plurality of first recesses1010extends partially into the insulating layer1004.

The plurality of second recesses1015define contours of the ring structure. Each of the plurality of second recesses1015extends through less than an entirety of the semiconductor layer1006. In some embodiments, at least one of the plurality of second recesses1015has a different depth than another of the plurality of second recesses1015. In some embodiments, the plurality of first recesses1010is formed simultaneously with the plurality of second recesses1015. In some embodiments, the plurality of first recesses1010are formed before or after the plurality of second recesses1015.

Returning toFIG.11, in operation1110the ring structure and the cooling structures are doped. The doping includes doping a first portion of the ring structure and a first portion of the cooling structures using a first dopant having a first dopant type; and doping a second portion of the ring structure and a second portion of the cooling structures using a second dopant having a second dopant type. The first dopant type is opposite to the second dopant type. In some embodiments, the doping includes ion implantation. In some embodiments, the doping includes deposition of a layer including dopants followed by a thermal process to drive the dopants into the ring structure and the cooling structures.

In some embodiments, the doping of the first portion of the ring structure and the first portion of the cooling structures includes a single doping step. In some embodiments, the doping of the first portion of the ring structure and the first portion of the cooling structures includes multiple doping steps. In some embodiments, all doping steps use a same species of dopant having the first dopant type. In some embodiments, at least one doping step uses a different species of dopant from another doping step. In some embodiments, each of the first portion of the ring structure and the first portion of the cooling structures have a same dopant concentration. In some embodiments, at least one of the first portion of the ring structure or the first portion of the cooling structure has a different dopant concentration from another of the first portion of the ring structure or the first portion of the cooling structure.

In some embodiments, the doping of the second portion of the ring structure and the second portion of the cooling structures includes a single doping step. In some embodiments, the doping of the second portion of the ring structure and the second portion of the cooling structures includes multiple doping steps. In some embodiments, all doping steps use a same species of dopant having the second dopant type. In some embodiments, at least one doping step uses a different species of dopant from another doping step. In some embodiments, each of the second portion of the ring structure and the second portion of the cooling structures have a same dopant concentration. In some embodiments, at least one of the second portion of the ring structure or the second portion of the cooling structure has a different dopant concentration from another of the second portion of the ring structure or the second portion of the cooling structure.

FIG.10Cis a cross-sectional view of a portion of a photonic system1000C having a MRM following one or more doping processes, in accordance with some embodiments. The photonic system1000C is similar to the photonic system1000B (FIG.10B), and similar elements have a same reference number. In comparison with the photonic system1000B (FIG.10B), the photonic system1000C includes a doped first portion1020of the cooling structures; and a doped second portion1030of the cooling structures. The photonic system1000C further includes doped portions1025and1027of the ring structure having dopants of a first type; and doped portions1035and1037of the ring structure having dopants of a second type, opposite the first type.

In some embodiments, the doped portion1025is similar to the doped region834a(FIG.8). In some embodiments, the doped portion1027is similar to the doped regions834band834c(FIG.8). The doped first portion1020provides electrical connection to a conductive material of a cooling element. In some embodiments, a dopant concentration of the doped regions1025and1027is similar to a dopant concentration of the doped first portion1020. In some embodiments, the dopant concentration of the doped regions1025or1027is different from the dopant concentration of the doped first portion1020. In some embodiments, a dopant species of the doped regions1025and1027is the same as a dopant species of the doped first portion1020. In some embodiments, the dopant species of the doped regions1025or1027is different from the dopant species of the doped first portion1020.

In some embodiments, the doped portion1035is similar to the doped region832a(FIG.8). In some embodiments, the doped portion1037is similar to the doped regions832band832c(FIG.8). The doped second portion1030provides electrical connection to a conductive material of the cooling element. In some embodiments, a dopant concentration of the doped regions1035and1037is similar to a dopant concentration of the doped second portion1030. In some embodiments, the dopant concentration of the doped regions1035or1037is different from the dopant concentration of the doped second portion1030. In some embodiments, a dopant species of the doped regions1035and1037is the same as a dopant species of the doped second portion1030. In some embodiments, the dopant species of the doped regions1035or1037is different from the dopant species of the doped second portion1030.

Returning toFIG.11, the method1100further includes operation1115in which a dielectric material is deposited over the doped ring structure and the doped cooling structures. The dielectric material fills a space between the ring structure and the cooling structures. The dielectric material extends above the ring structure and the cooling structures. In some embodiments, the dielectric material includes silicon oxide, silicon nitride, silicon oxynitride, or another suitable dielectric material. In some embodiments, the dielectric material is deposited using CVD, PVD, ALD, or another suitable deposition process. In some embodiments, a planarization process, such as a chemical mechanical polishing (CMP) process, follows the deposition process in order to form a flat top surface for subsequent processing.

FIG.10Dis a cross-sectional view of a portion of a photonic system1000D having a MRM following deposition of a dielectric material, in accordance with some embodiments. The photonic system1000D is similar to the photonic system1000C (FIG.10C), and similar elements have a same reference number. In comparison with the photonic system1000C (FIG.10C), the photonic system1000D includes a dielectric material1040over the ring structure and the cooling structures.

The dielectric material1040fills spaces between the ring structure and the cooling structures. The dielectric material1040extends over a top of the ring structure and the cooling structures. In some embodiments, a material of the dielectric material1040includes a same material as the insulating layer1004. In some embodiments, the material of the dielectric material1040is different from the material of the insulating layer1004.

Returning toFIG.11, the method1100includes operation1120in which the dielectric material is etched to define an opening for a conductive material for a heater. In some embodiments, the operation1120includes a single etching process. In some embodiments, the operation1120includes multiple etching processes. In some embodiments, the operation1120includes a wet etching process or a dry etching process. In some embodiments, the etching process further includes a photolithography process to define the locations where material is removed by the etching process.

FIG.10Eis a cross-sectional view of a portion of a photonic system1000E having an MRM following etching of the dielectric material, in accordance with some embodiments. The photonic system1000E is similar to the photonic system1000D (FIG.10D), and similar elements have a same reference number. In comparison with the photonic system1000D (FIG.10D), the photonic system1000E includes an opening1050. The opening1050is positioned to receive a conductive layer of the heater. The opening1050is proximate the ring structure. In some embodiments, the opening1050is aligned with edges of the ring structure. In some embodiments, the opening1050is narrower than the ring structure. In some embodiments, the opening1050is wider than the ring structure. The opening1050is offset from sidewalls of the cooling structures1020and1030.

Returning toFIG.11, the method1100further includes operation1125in which a conductive material is deposited in the opening. The conductive material at least partially fills the opening. In some embodiments, the conductive material includes copper, aluminum, tungsten, cobalt, alloys therefor, or another suitable conductive material. In some embodiments, the conductive material is deposited using CVD, PVD, ALD, sputtering, plating or another suitable deposition process. In some embodiments, a planarization process, such as a CMP process, follows the deposition process in order to form a flat top surface for subsequent processing. In some embodiments, an additional layer of dielectric material is deposited over the conductive material.

FIG.10Fis a cross-sectional view of a portion of a photonic system1000F having a MRM following deposition of a conductive material, in accordance with some embodiments. The photonic system1000F is similar to the photonic system1000E (FIG.10E), and similar elements have a same reference number. In comparison with the photonic system1000E (FIG.10E), the photonic system1000F includes a conductive material1060over the ring structure and a dielectric material1065over the conductive material1060.

The conductive material1060is proximate the ring structure to permit heating of the ring structure. In some embodiments, the conductive material1060includes copper, aluminum, tungsten, cobalt, alloys therefor, or another suitable conductive material. In some embodiments, the conductive material1060is aligned with edges of the ring structure. In some embodiments, the conductive material1060is narrower than the ring structure. In some embodiments, the conductive material1060is wider than the ring structure. The conductive material1060is offset from sidewalls of the cooling structures1020and1030, such that the conductive material1060does not overlap the cooling structures1020and1030in a plan view.

The dielectric material1065is over the conductive material1060. The dielectric material1065over the ring structure and the cooling structures. In some embodiments, a material of the dielectric material1065includes a same material as the insulating layer1004and the dielectric material1040. In some embodiments, the material of the dielectric material1065is different from the material of at least one of the insulating layer1004or the dielectric material1040. In some embodiments, an interface exists between the dielectric material1065and the dielectric material1040. In some embodiments, no interface exists between the dielectric material1065and the dielectric material1040.

Returning toFIG.11, the method1100includes operation1130in which the dielectric material is etched to define an opening for a conductive material for a cooling element. In some embodiments, the operation1130includes a single etching process. In some embodiments, the operation1130includes multiple etching processes. In some embodiments, the operation1130includes a wet etching process or a dry etching process. In some embodiments, the etching process further includes a photolithography process to define the locations where material is removed by the etching process.

FIG.10Gis a cross-sectional view of a portion of a photonic system1000G having an MRM following etching of the dielectric material, in accordance with some embodiments. The photonic system1000G is similar to the photonic system1000F (FIG.10F), and similar elements have a same reference number. In comparison with the photonic system1000F (FIG.10F), the photonic system1000G includes an opening1070. The opening1070is positioned to expose the doped portions of the cooling structure. In some embodiments, the opening1070exposes an entirety of each of the portions1020and1030of the cooling structure. In some embodiments, the opening1070exposes less than an entirety of at least one of the portion1020or the portion1030.

Returning toFIG.11, the method1100further includes operation1135in which a conductive material is deposited in the opening. The conductive material at least partially fills the opening. In some embodiments, the conductive material includes copper, aluminum, tungsten, cobalt, alloys therefor, or another suitable conductive material. In some embodiments, the conductive material is deposited using CVD, PVD, ALD, sputtering, plating or another suitable deposition process. In some embodiments, a planarization process, such as a CMP process, follows the deposition process in order to form a flat top surface for subsequent processing. In some embodiments, an additional layer of dielectric material is deposited over the conductive material.

FIG.10His a cross-sectional view of a portion of a photonic system1000H having a MRM following deposition of a conductive material, in accordance with some embodiments. The photonic system1000H is similar to the photonic system1000G (FIG.10G), and similar elements have a same reference number. In comparison with the photonic system1000G (FIG.10G), the photonic system1000H includes a conductive material1080over electrically connected to the portions1020and1030of the cooling element and a dielectric material1085over the conductive material1080.

The conductive material1080is electrically connected to the portions1020and1030of the cooling structures in order to cause cooling of the ring structure as current flows through the cooling structures. In some embodiments, the conductive material1080includes copper, aluminum, tungsten, cobalt, alloys therefor, or another suitable conductive material. In some embodiments, a material of the conductive material1080is a same material as the conductive material1060. In some embodiments, a material of the conductive material1080is different from the conductive material1060.

The dielectric material1085is over the conductive material1080. The dielectric material1085over the ring structure and the cooling structures. In some embodiments, a material of the dielectric material1085includes a same material as the insulating layer1004, the dielectric material1040and the dielectric material1065. In some embodiments, the material of the dielectric material1085is different from the material of at least one of the insulating layer1004, the dielectric material1040, or the dielectric material1065. In some embodiments, an interface exists between the dielectric material1065and the dielectric material1085. In some embodiments, no interface exists between the dielectric material1065and the dielectric material1085.

One of ordinary skill in the art would recognize that the method1100and the structures ofFIGS.10A-10Hare merely exemplary. One of ordinary skill in the art would understand that the method1100and the structures ofFIGS.10A-10Hare adjustable to accommodate different designs for the photonic system, such as locating a conductive element for a heater or cooling element on a backside of the substrate, e.g., semiconductor layer1002.

One of ordinary skill in the art would understand that additional operations are able to be included in the method1100. For example, in some embodiments, a waveguide is formed from the semiconductor layer1006. One of ordinary skill in the art would understand that at least one operation of the method1100is omitted. For example, in some embodiments, the operation1105is omitted and a growth process, such as an epitaxial process, is used to define the ring structure and the cooling structures. One of ordinary skill in the art would understand that an order of operations of the method1100are adjusted. For example, in some embodiments, the operations1130and1135are performed prior to the operations1120and1125in order to form a structure where the conductive element of a cooling element is closer to the ring structure than the conductive element of a heater.

An aspect of this description relates to a photonic system. The photonic system includes a waveguide. The photonic system further includes a micro ring modulator (MRM) spaced from the waveguide. The photonic system further includes a heater configured to increase a temperature of the MRM in response to the heater receiving a first voltage. The photonic system further includes a cooling element configured to decrease a temperature of the MRM in response to the cooling element receiving a second voltage. In some embodiments, the photonic system further includes a controller. The controller is configured to generate a first signal for supplying the first voltage to the heater, and generate a second signal for supplying the second voltage to the cooling element. In some embodiments, the cooling element includes a cooling conductive element, wherein the cooling conductive element overlaps the MRM in a top view. In some embodiments, the heater includes a heater conductive element, wherein the heater conductive element overlaps the MRM in the top view. In some embodiments, the heater conductive element is between the cooling conductive element and the MRM. In some embodiments, the cooling conductive element is between the heater conductive element and the MRM. In some embodiments, the photonic system further includes a substrate, wherein the MRM is on a first side of the substrate, and the heater conductive element is on a second side of the substrate opposite the first side of the substrate. In some embodiments, the waveguide is a curved waveguide. In some embodiments, the photonic system further includes a second waveguide, wherein the MRM is between the waveguide and the second waveguide. In some embodiments, the MRM is configured to couple an optical signal out of the waveguide, and the MRM is configured to couple the optical signal into the second waveguide.

An aspect of this description relates to a photonic system. The photonic system includes a waveguide. The photonic system further includes a micro ring modulator (MRM) spaced from the waveguide. The photonic system further includes a heater configured to increase a temperature of the MRM. The heater includes at least one first doped region, wherein each first doped region of the at least one first doped region has a first dopant type; and at least one second doped region, wherein each second doped region of the at least one second doped region has a second dopant type opposite the first dopant type. The photonic system further includes a cooling element configured to decrease a temperature of the MRM. The cooling element includes a plurality of third doped regions, wherein each third doped region of the plurality of third doped regions has the first dopant type; and a plurality of fourth doped regions, wherein each fourth doped region of the plurality of fourth doped regions has the second dopant type. In some embodiments, the at least one first doped region is a plurality of first doped regions, and adjacent first doped regions of the plurality of first doped regions are discontinuous with one another. In some embodiments, the at least one first doped region directly contacts the MRM. In some embodiments, third doped regions of the plurality of third doped regions and fourth doped regions of the plurality of fourth doped regions are in an alternating pattern arrangement. In some embodiments, a region of the MRM closest to the waveguide is exposed by both the at least one first doped region and the at least one second doped region. In some embodiments, the photonic system further includes a controller, wherein the controller is configured to control a first voltage supplied to the at least one first doped region, and control a second voltage supplied to the plurality of third doped regions. In some embodiments, the photonic system has a slab-free arrangement.

An aspect of this description relates to a method of making a photonic system. The method includes etching a wafer to define a micro ring modulator (MRM) and a plurality of cooling structures. The method further includes doping a first portion of the MRM with a first dopant having a first dopant type. The method further includes doping a second portion of the MRM with a second dopant having a second dopant type different from the first dopant type. The method further includes doping a first cooling structure of the plurality of cooling structures with a third dopant having the first dopant type. The method further includes doping a second cooling structure of the plurality of cooling structures with a fourth dopant having the second dopant type. The method further includes forming a first conductive element proximate the MRM. The method further includes forming a second conductive element electrically connected to the first cooling structure and the second cooling structure. In some embodiments, forming the second conductive element includes forming the second conductive element on an opposite side of the first conductive element from the MRM. In some embodiments, the method further includes depositing a dielectric material over the doped first cooling structure, wherein the dielectric material fills a space between the first cooling structure and the MRM.