Patent Description:
Lidar systems emit one or more beams of light and identify distances to and speeds of various objects in the operational environment of the lidar system based upon reflections of the beams from the objects. Lidar systems incorporate various optical and electrical elements that facilitate emission and reception of light. By way of example, a lidar system can include a laser and a high quality factor (Q) whispering gallery mode resonator along with various other componentry to control emission and reception of the light. The laser and the resonator are optically coupled, such that light from the laser is provided to the resonator, circulates inside the resonator undergoing total internal reflection, and is provided back from the resonator to the laser.

An example of a type of high Q whispering gallery mode resonator that is often used in lidar systems is a disk resonator. Conventional designs of disk resonators can intrinsically support a plurality of modes per each free spectral range (FSR). Mode positions in the traditional disk resonators can be determined by resonator geometry, which can have variations due to limited fabrication precision. Accordingly, many fabricated disk resonators can have side modes near a working mode (e.g., within a certain frequency range), which can render such resonators unusable. Thus, resonator production yield for conventional disk-shaped resonators used for lidar systems can be detrimentally impacted.

<CIT> discloses a FM LIDAR system that includes a frequency modulated LIDAR system that incorporates a laser source that is optically coupled to a whispering gallery mode optical resonator. Light from the laser that is coupled into the whispering gallery mode optical resonator is coupled back out as a returning counterpropagating wave having a frequency characteristic of a whispering gallery mode of the optical resonator. This returning wave is used to reduce the linewidth of the source laser by optical injection. Modulation of the optical properties of the whispering gallery mode optical resonator results in modulation of the frequency of the frequencies supported by whispering gallery modes of the resonator, and provides a method for producing highly linear and reproducible optical chirps that are highly suited for use in a LIDAR system.

<CIT> discloses whispering-gallery-mode resonators configured to support only a single whispering gallery mode.

<CIT> discloses devices having whispering-gallery-mode resonators configured to meet requirements of various applications and facilitate fabrication of such devices.

The following is a brief summary of subject matter that is described in greater detail herein. This summary is not intended to be limiting as to the scope of the claims.

Described herein are various technologies that pertain to asymmetric high Q whispering gallery mode resonators. An asymmetric whispering gallery mode resonator device can include an asymmetric whispering gallery mode resonator disk formed of a transparent material. For instance, the transparent material can be an electrooptic material. The asymmetric whispering gallery mode resonator disk can include an axial surface along a perimeter of the asymmetric whispering gallery mode resonator disk. A first midplane passes through the axial surface dividing the axial surface into symmetrical halves. The asymmetric whispering gallery mode resonator disk can further include a top surface and a bottom surface, where the bottom surface is substantially parallel to the top surface. A second midplane can be substantially equidistant between the top surface and the bottom surface. The first midplane and the second midplane are non-coextensive. The asymmetric whispering gallery mode resonator disk can further include a first chamfered edge between the top surface and the axial surface, and a second chamfered edge between the bottom surface and the axial surface. The axial surface, the first chamfered edge, and the second chamfered edge can form a convex side structure of the asymmetric whispering gallery mode resonator disk. Moreover, the asymmetric whispering gallery mode resonator device can include a first electrode on the top surface of the asymmetric whispering gallery mode resonator disk and a second electrode on the bottom surface of the asymmetric whispering gallery mode resonator disk.

The asymmetric whispering gallery mode resonator device can support a fundamental mode located in the first midplane. Due to the first midplane and the second midplane being non-coextensive, the plane in which the fundamental mode is located is non-coextensive with the second midplane (e.g., the fundamental mode is not in a midplane substantially equidistant between the top surface and the bottom surface of the asymmetric whispering gallery mode resonator disk). For example, the first midplane can be shifted relative to the second midplane. According to another example, the first midplane can be tilted relative to the second midplane. The positioning of the fundamental mode in the asymmetric whispering gallery mode resonator disk as described herein can enable suppression of side mode(s) in the asymmetric whispering gallery mode resonator device.

Pursuant to various embodiments, the first midplane in which the fundamental mode is located can be shifted relative to the second midplane, which is substantially equidistant between the top surface and the bottom surface. In such embodiments, the first midplane that passes through the axial surface dividing the axial surface into symmetrical halves can be shifted towards either the top surface or the bottom surface relative to the second midplane. Thus, a first distance between the first midplane and the top surface can differ from a second distance between the first midplane and the bottom surface. Accordingly, a position of the fundamental mode located in the first midplane in such embodiments can be shifted towards either the top surface or the bottom surface as opposed to being located in the second midplane equidistant between the top surface and the bottom surface of resonator disk. The shifting of the position of the fundamental mode can cause side mode(s) nearby the fundamental mode to suffer losses due to being positioned closer to an electrode of the asymmetric whispering gallery mode resonator device (e.g., the side mode(s) can experience losses due to interaction with metal of the electrode).

In accordance with other embodiments, the first midplane in which the fundamental mode is located can be tilted relative to the second midplane. Accordingly, the first midplane that passes through the axial surface of the asymmetric whispering gallery mode resonator disk dividing the axial surface into symmetrical halves and the second midplane that is substantially equidistant between the top surface and the bottom surface can be tilted relative to each other. The first midplane and the second midplane can intersect within the asymmetric whispering gallery mode resonator disk. The tilting of the position of the first midplane in which the fundamental mode is located can cause side mode(s) nearby the fundamental mode to suffer losses due to being positioned closer to an electrode of the asymmetric whispering gallery mode resonator device.

The above summary presents a simplified summary in order to provide a basic understanding of some aspects of the systems and/or methods discussed herein. This summary is not an extensive overview of the systems and/or methods discussed herein. It is not intended to identify key/critical elements or to delineate the scope of such systems and/or methods. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

Various technologies pertaining to asymmetric whispering gallery mode resonators are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more aspects. Further, it is to be understood that functionality that is described as being carried out by certain system components may be performed by multiple components. Similarly, for instance, a component may be configured to perform functionality that is described as being carried out by multiple components.

As used herein, the terms "component" and "system" are intended to encompass computer-readable data storage that is configured with computer-executable instructions that cause certain functionality to be performed when executed by a processor. The computer-executable instructions may include a routine, a function, or the like. The terms "component" and "system" are also intended to encompass one or more optical elements that can be configured or coupled together to perform various functionality with respect to an optical signal. It is also to be understood that a component or system may be localized on a single device or distributed across several devices. Further, as used herein, the term "exemplary" is intended to mean "serving as an illustration or example of something.

Referring now to the drawings, <FIG> illustrates a cross-sectional view of an exemplary asymmetric whispering gallery mode resonator device <NUM> (also referred to herein as a resonator device <NUM>). As used herein, the terms "resonator device" and "resonator" are used interchangeably. The resonator device <NUM> includes an asymmetric whispering gallery mode resonator disk <NUM> (also referred to herein as a resonator disk <NUM>) formed of a transparent material. According to various embodiments, the transparent material can be an electrooptic material. For example, the asymmetric whispering gallery mode resonator disk <NUM> can be formed of any of various crystalline materials such as calcium fluoride, magnesium fluoride, lithium niobate, lithium tantalate, silicon, or the like. However, it is contemplated that the resonator disk <NUM> can be formed of a transparent material other than an electrooptic material.

The asymmetric whispering gallery mode resonator disk <NUM> includes an axial surface <NUM> along a perimeter of the asymmetric whispering gallery mode resonator disk <NUM>. A first midplane <NUM> passes through the axial surface <NUM> dividing the axial surface <NUM> into symmetrical halves. Thus, as shown, a top half of the axial surface <NUM> is above the first midplane <NUM> and a bottom half of the axial surface <NUM> is below the first midplane <NUM>.

The asymmetric whispering gallery mode resonator disk <NUM> further includes a top surface <NUM>, a bottom surface <NUM>, a first chamfered edge <NUM>, and a second chamfered edge <NUM>. The bottom surface <NUM> is substantially parallel to the top surface <NUM>. A second midplane <NUM> is substantially equidistant between the top surface <NUM> and the bottom surface <NUM>. The second midplane <NUM> and the first midplane <NUM> are non-coextensive. Moreover, the first chamfered edge <NUM> is between the top surface <NUM> and the axial surface <NUM>, and the second chamfered edge <NUM> is between the bottom surface <NUM> and the axial surface <NUM>. Further, the axial surface <NUM>, the first chamfered edge <NUM>, and the second chamfered edge <NUM> form a convex side structure of the asymmetric whispering gallery mode resonator disk <NUM> (e.g., the axial surface <NUM>, the first chamfered edge <NUM>, and the second chamfered edge have a convex geometry from a point of view external to the resonator device <NUM>). The convex side structure of the asymmetric whispering gallery mode resonator disk <NUM> can simplify fabrication, polishing, cleaning, etc. of the resonator device <NUM>.

The resonator device <NUM> can further include chamfered edges <NUM>-<NUM> with differing widths. In particular, a width of the first chamfered edge <NUM> can differ from a width of the second chamfered edge <NUM>. In the example shown in <FIG>, the width of the first chamfered edge <NUM> can be greater than the width of the second chamfered edge <NUM>.

The resonator device <NUM> further includes a first electrode <NUM> on the top surface <NUM> of the asymmetric whispering gallery mode resonator disk <NUM> and a second electrode <NUM> on the bottom surface <NUM> of the asymmetric whispering gallery mode resonator disk <NUM>. Substantially any type of electrodes <NUM>-<NUM> can be on the top and bottom surfaces <NUM>-<NUM> of the asymmetric whispering gallery mode resonator disk <NUM>. According to an illustration, an optical insulator can be adjacent to the material of the asymmetric whispering gallery mode resonator disk <NUM>. Further, a layer of a bonding metal, such as chromium or titanium, can be on the optical insulator, and the electrode can be on the bonding metal. Following this illustration, an optical insulator layer and a bonding metal layer can be between the top surface <NUM> and the first electrode <NUM>. Likewise, an optical insulator layer and a bonding metal layer can be between the bottom surface <NUM> and the second electrode <NUM>. However, it is to be appreciated that the claimed subject matter is not limited to the foregoing illustration. Moreover, according to an example, the electrodes <NUM>-<NUM> can be formed of gold; yet, it is contemplated that the electrodes <NUM>-<NUM> can be formed of other materials.

According to various embodiments, a thickness <NUM> of the asymmetric whispering gallery mode resonator disk <NUM> can be in a range between <NUM> and <NUM> micrometers. As described herein, ranges can be inclusive ranges; thus, <NUM> and <NUM> micrometers are intended to fall within the scope of the aforementioned range. According to an example, the thickness <NUM> of the asymmetric whispering gallery mode resonator disk <NUM> can be <NUM> micrometers, <NUM> micrometers, or the like. Further, a diameter <NUM> of the asymmetric whispering gallery mode resonator disk <NUM> can be in a range between <NUM> and <NUM> millimeters. Pursuant to an example, the diameter <NUM> of the asymmetric whispering gallery mode resonator disk <NUM> can be <NUM> millimeters. However, it is to be appreciated that differing thicknesses <NUM> and diameters <NUM> are intended to fall within the scope of the hereto appended claims since the approaches described herein can be scaled (e.g., the thickness <NUM> need not be in the range between <NUM> and <NUM> micrometers, the diameter <NUM> need not be in the range between <NUM> and <NUM> millimeters).

As noted above, the second midplane <NUM> is substantially equidistant between the top surface <NUM> and the bottom surface <NUM>. A distance between the top surface <NUM> and the second midplane <NUM> can be substantially equal to a distance between the bottom surface <NUM> and the second midplane <NUM>. Thus, the distance between the top surface <NUM> and the second midplane <NUM> can be half the thickness <NUM> of the asymmetric whispering gallery mode resonator disk <NUM>, and the distance between the bottom surface <NUM> and the second midplane <NUM> can be half the thickness <NUM> of the asymmetric whispering gallery mode resonator disk <NUM>.

An optical whispering gallery mode resonator device can have a set of optical mode families that it supports. Frequencies of modes in each family can be determined by material properties. Further, the set of mode families can be determined by a shape of the whispering gallery mode resonator device. The asymmetric whispering gallery mode resonator device <NUM> can support a fundamental mode <NUM> located in the first midplane <NUM>. A fundamental mode can also be referred to as a lidar working mode. The fundamental mode <NUM> in the first midplane <NUM> is located at an outer extremity towards the perimeter of the asymmetric whispering gallery mode resonator disk <NUM> (e.g., towards the axial surface <NUM> in the first midplane <NUM>).

Moreover, side modes (also referred to as higher order modes) can be located progressively away from a location of a fundamental mode in a whispering gallery mode resonator device. Side modes can exist in vicinity of the fundamental mode, resulting in dense resonator spectrum. The side modes can include transverse and radial modes. Transverse modes can extend in an axial (e.g., up and down) direction from the location of the fundamental mode, and radial modes can extend in the radial direction from the location of the fundamental mode towards the center of a resonator device. A side mode <NUM> and a side mode <NUM> are depicted in <FIG> for purposes of illustration. It is contemplated that the claimed subject matter is not limited to the resonator device <NUM> including two side modes.

Due to the first midplane <NUM> and the second midplane <NUM> being non-coextensive, a plane in which the fundamental mode <NUM> is located is non-extensive with the second midplane <NUM>. Accordingly, the fundamental mode <NUM> is not positioned in the second midplane <NUM> substantially equidistant between the top surface <NUM> and the bottom surface <NUM>. In the embodiment of the resonator device <NUM> depicted in <FIG>, the asymmetric whispering gallery mode resonator disk <NUM> can have the first midplane <NUM> shifted related to the second midplane <NUM>. Thus, a position of the fundamental mode <NUM> located in the first midplane <NUM> can be shifted towards either the top surface <NUM> or the bottom surface <NUM> as opposed to being located in the second midplane <NUM> equidistant between the top surface <NUM> and the bottom surface <NUM> of the resonator disk <NUM>. In particular, <FIG> shows the first midplane <NUM> being shifted towards the bottom surface <NUM> relative to the second midplane <NUM>. Accordingly, a first distance between the first midplane <NUM> and the top surface <NUM> can differ from a second distance between the first midplane <NUM> and the bottom surface <NUM> (e.g., the distance between the first midplane <NUM> and the bottom surface <NUM> is less than the distance between the first midplane <NUM> and the top surface <NUM> in the example depicted in <FIG>).

Shifting of the position of the fundamental mode <NUM> can cause side mode(s) nearby the fundamental mode <NUM> to suffer losses due to be positioned closer to an electrode of the asymmetric whispering gallery mode resonator device <NUM>. As depicted in <FIG>, the number of side modes with a large axial extent (e.g., along a disk axis, up and down) can be lowered (compared to a symmetric whispering gallery mode resonator device as shown in <FIG>) by reducing the amount of space in which such side modes can exist. The foregoing can be achieved in the resonator device <NUM> by placing the fundamental mode plane (e.g., the first midplane <NUM>) closer to the bottom surface <NUM> and the second electrode <NUM>. Thus, side mode(s) (e.g., transverse mode(s) with high axial extent) between the first midplane <NUM> and the bottom surface <NUM> can experience losses due to interaction with metal of the second electrode <NUM>, while the fundamental mode <NUM> can remain relatively unaffected.

Now turning to <FIG>, illustrated is a cross-sectional view of another exemplary asymmetric whispering gallery mode resonator device <NUM> (resonator device <NUM>). Similar to the resonator device <NUM> of <FIG>, the resonator device <NUM> includes an asymmetric whispering gallery mode resonator disk <NUM> (resonator disk <NUM>) formed of a transparent material (e.g., an electrooptic material). Similar to the resonator disk <NUM> of <FIG>, the asymmetric whispering gallery mode resonator disk <NUM> includes an axial surface <NUM> along a perimeter, where a first midplane <NUM> passes through the axial surface <NUM> dividing the axial surface <NUM> into symmetrical halves.

Similar to the resonator disk <NUM> of <FIG>, the asymmetric whispering gallery mode resonator disk <NUM> also includes a top surface <NUM>, a bottom surface <NUM>, a first chamfered edge <NUM>, and a second chamfered edge <NUM>. The bottom surface <NUM> and the top surface <NUM> are substantially parallel to each other, and a second midplane <NUM> is substantially equidistant between the top surface <NUM> and the bottom surface <NUM>. Moreover, the first midplane <NUM> and the second midplane <NUM> are non-coextensive. Further, the first chamfered edge <NUM> is between the top surface <NUM> and the axial surface <NUM>, and the second chamfered edge <NUM> is between the bottom surface <NUM> in the axial surface <NUM>. The first chamfered edge <NUM>, the axial surface <NUM>, and the second chamfered edge <NUM> form a convex side structure of the asymmetric whispering gallery mode resonator disk <NUM>. In the example shown in <FIG>, widths of the first chamfered edge <NUM> and the second chamfered edge <NUM> can be substantially similar.

The asymmetric whispering gallery mode resonator device <NUM> also includes a first electrode <NUM> and a second electrode <NUM>. The first electrode <NUM> is on the top surface <NUM> of the asymmetric whispering gallery mode resonator disk <NUM>. Moreover, the second electrode <NUM> is on the bottom surface <NUM> of the asymmetric whispering gallery mode resonator disk <NUM>.

Again, it is contemplated that a thickness of the asymmetric whispering gallery mode resonator disk <NUM> can be in a range between <NUM> and <NUM> micrometers (e.g., <NUM> micrometers, <NUM> micrometers). Moreover, it is contemplated that a diameter of the asymmetric whispering gallery mode resonator disk <NUM> can be in a range between <NUM> and <NUM> millimeters (e.g., <NUM> millimeters). Yet, the claimed subject matter is not limited to the foregoing examples since the approaches described herein can be scaled (e.g., the thickness need not be in the range between <NUM> and <NUM> micrometers, the diameter need not be in the range between <NUM> and <NUM> millimeters).

The asymmetric whispering gallery mode resonator device <NUM> can support a fundamental mode <NUM> located in the first midplane <NUM>. Further, although not shown, side mode(s) can be located progressively away from a location of the fundamental mode <NUM> in the resonator device <NUM>.

Due to the first midplane <NUM> and the second midplane <NUM> being non-coextensive, a plane in which the fundamental mode <NUM> is located is non-extensive with the second midplane <NUM>. Accordingly, the fundamental mode <NUM> is not positioned in the second midplane <NUM> substantially equidistant between the top surface <NUM> and the bottom surface <NUM>. In the embodiment of the resonator device <NUM> shown in <FIG>, the first midplane <NUM> and the second midplane <NUM> of the asymmetric whispering gallery mode resonator disk <NUM> can be tilted relative to each other. The first midplane <NUM> and the second midplane <NUM> intersect within the asymmetric whispering gallery mode resonator disk <NUM> (at intersection <NUM>). Tilting of the fundamental mode plane (e.g., the first midplane <NUM>) can be obtained by mounting a substrate from which the resonator device <NUM> is formed at an angle before resonator fabrication.

The tilting of the position of the first midplane <NUM> in which the fundamental mode <NUM> is located can cause side mode(s) nearby the fundamental mode <NUM> to suffer losses due to being positioned closer to an electrode of the asymmetric whispering gallery mode resonator device <NUM>. Similar to the resonator device <NUM> of <FIG>, the resonator device <NUM> of <FIG> can reduce the number of side modes with large axial extent (e.g., along the disk axis, up and down) as compared to a symmetrical whispering gallery mode resonator device (e.g., as shown in <FIG>) by reducing the amount of space in which such side modes can exist. More particularly, an angle between the fundamental mode axis (e.g., the first midplane <NUM>) and the resonator disk axis (e.g., the second midplane <NUM>) can be introduced. The angle between the first midplane <NUM> and the second midplane <NUM> can cause the fundamental mode plane (e.g., the first midplane <NUM> in which the fundamental mode <NUM> is located) to wobble up and down in the resonator device <NUM> and approach closer to edges of the resonator device <NUM>. Thus, side mode(s) (e.g., transverse mode(s) with high axial extent) can experience losses due to interaction with metal of the electrodes <NUM>-<NUM>, while the fundamental mode <NUM> can remain relatively unaffected.

In the example shown in <FIG>, an offset A <NUM> can be greater than an offset B <NUM>. The offset A <NUM> is between the first midplane <NUM> and the second midplane <NUM> on one side of the asymmetric whispering gallery mode resonator disk <NUM>, and the offset B <NUM> is between the first midplane <NUM> and the second midplane <NUM> on the opposite side of the whispering gallery mode resonator disk <NUM>. The wobble can be set forth as follows: Wobble = |Offset A| + |Offset B|. It is also contemplated that, according to various embodiments, the offset A can equal the offset B; thus, in such embodiments, the asymmetric whispering gallery mode resonator disk can have a symmetric tilt.

Pursuant to various examples, a minimum mode distance from a surface can be <NUM>. Moreover, an angle can be <NUM>. <NUM> degrees; yet, the claimed subject matter is not limited to the foregoing examples.

Referring to <FIG>, illustrated is a cross-sectional view of an exemplary symmetric whispering gallery mode resonator device <NUM> (resonator device <NUM>) outside the claimed subject-matter. The resonator device <NUM> includes a symmetric whispering gallery mode resonator disk <NUM> (resonator disk <NUM>) formed of a transparent material (e.g., an electrooptic material). The symmetric whispering gallery mode resonator disk <NUM> includes an axial surface <NUM> along a perimeter, where a midplane <NUM> passes through the axial surface <NUM> dividing the axial surface <NUM> into symmetrical halves.

The symmetrical whispering gallery mode resonator disk <NUM> also includes a top surface <NUM>, a bottom surface <NUM>, a first chamfered edge <NUM>, and a second chamfered edge <NUM>. In the example of <FIG>, the midplane <NUM> is also substantially equidistant between the top surface <NUM> and the bottom surface <NUM>. The symmetric whispering gallery mode resonator device <NUM> also includes a first electrode <NUM> on the top surface <NUM> and a second electrode <NUM> on the bottom surface <NUM>.

The symmetric whispering gallery mode resonator device <NUM> supports a fundamental mode <NUM> in the midplane <NUM> of the resonator device <NUM>. Moreover, side modes can be located progressively away from the fundamental mode in the midplane of <NUM>. Moreover, side modes (e.g., a side mode <NUM>, a side mode <NUM>, a side mode <NUM>, and a side mode <NUM>) can be located in vicinity of the fundamental mode <NUM>. Four side modes <NUM>-<NUM> are depicted for purposes of illustration. As described above, the asymmetric whispering gallery mode resonator device <NUM> of <FIG> and the asymmetric whispering gallery mode resonator device <NUM> of <FIG> can reduce the number of side modes relative to the symmetric whispering gallery mode resonator device <NUM> shown in <FIG> (e.g., by having the fundamental mode plane differ from the midplane of the resonator device).

Now turning to <FIG>, illustrated are cross-sectional views of portions of exemplary convex side structures of a whispering gallery mode resonator disk (e.g., the asymmetric whispering gallery mode resonator disk <NUM> of <FIG>, the asymmetric whispering gallery mode resonator disk <NUM> of <FIG>, the symmetric whispering gallery mode resonator disk <NUM> of <FIG>). The convex side structures include an axial surface (e.g., the axial surface <NUM>, the axial surface <NUM>, the axial surface <NUM>), a first chamfered edge (e.g., the first chamfered edge <NUM>, the first chamfered edge <NUM>, the first chamfered edge <NUM>), and a second chamfered edge (e.g., the second chamfered edge <NUM>, the second chamfered edge <NUM>, the second chamfered edge <NUM>). An angle of the first chamfered edge relative to the axial surface can be in a range between <NUM> and <NUM> degrees. Moreover, an angle of the second chamfered edge relative to the axial surface can be in a range between <NUM> and <NUM> degrees.

With reference to <FIG>, depicted are an axial surface <NUM>, a first chamfered edge <NUM>, and a second chamfered edge <NUM> of a convex side structure of a whispering gallery mode resonator disk. An angle <NUM> of the first chamfered edge <NUM> relative to the axial surface <NUM> can be approximately <NUM> degrees. Similarly, an angle <NUM> of the second chamfered edge <NUM> relative to the axial surface <NUM> can be approximately <NUM> degrees.

Now turning to <FIG>, illustrated are an axial surface <NUM>, a first chamfered edge <NUM>, and a second chamfered edge <NUM> of another convex side structure of a whispering gallery mode resonator disk. An angle <NUM> of the first chamfered edge <NUM> relative to the axial surface <NUM> can be approximately <NUM> degrees. Similarly, an angle <NUM> of the second chamfered edge <NUM> relative to the axial surface <NUM> can be approximately <NUM> degrees.

The convex side structure shown in <FIG> (e.g., the angle <NUM> and the angle <NUM> each being approximately <NUM> degrees) can reduce coupling of side modes to a prism coupler as compared to the convex side structure shown in <FIG> (e.g., the angle <NUM> and the angle <NUM> each being approximately <NUM> degrees). However, electrical tuneability of the convex side structure shown in <FIG> can be reduced as compared to the convex side structure shown in <FIG> since metal of the electrodes is moved farther away from the axial surface <NUM> in the convex side structure of <FIG>.

The convex nature of the side structures (e.g., the axial surface, the first chamfered edge, and the second chamfered edge) in the examples set forth herein can be easier to make, polish, and clean as compared to whispering gallery mode resonator disks that include concave side structures. Moreover, while shown as having substantially similar angles between the first chamfered edge relative to the axial surface and the second chamfered edge relative to the axial surface in <FIG>, it is to be appreciated that such angles can differ (e.g., the angle <NUM> of the first chamfered edge <NUM> relative to the axial surface <NUM> can differ from the angle <NUM> of the second chamfered edge <NUM> relative to the axial surface <NUM>, the angle <NUM> of the first chamfered edge <NUM> relative to the axial surface <NUM> can differ from the angle <NUM> of the second chamfered edge <NUM> relative to the axial surface <NUM>).

<FIG> depict cross-sectional views of portions of other exemplary convex side structures of a whispering gallery mode resonator disk (e.g., the asymmetric whispering gallery mode resonator disk <NUM> of <FIG>, the asymmetric whispering gallery mode resonator disk <NUM> of <FIG>, the symmetric whispering gallery mode resonator disk <NUM> of <FIG>). The convex side structures include an axial surface (e.g., the axial surface <NUM>, the axial surface <NUM>, the axial surface <NUM>, the axial surface <NUM>, the axial surface <NUM>), a first chamfered edge (e.g., the first chamfered edge <NUM>, the first chamfered edge <NUM>, the first chamfered edge <NUM>, the first chamfered edge <NUM>, the first chamfered edge <NUM>), and a second chamfered edge (e.g., the second chamfered edge <NUM>, the second chamfered edge <NUM>, the second chamfered edge <NUM>, the second chamfered edge <NUM>, the second chamfered edge <NUM>).

Now referring to <FIG>, illustrated are an axial surface <NUM>, a first chamfered edge <NUM>, and a second chamfered edge <NUM>. As shown in <FIG>, the axial surface <NUM>, the first chamfered edge <NUM>, and the second chamfered edge <NUM> are polished. <FIG> depicts another example of an axial surface <NUM>, a first chamfered edge <NUM>, and the second chamfered edge <NUM>. In the example of <FIG>, the axial surface <NUM> is polished, whereas the first chamfered edge <NUM> and the second chamfered edge <NUM> are unpolished. Side mode(s) can be suppressed in the example set forth in <FIG>, where the first chamfered edge <NUM> and the second chamfered edge <NUM> are unpolished. More particularly, the unpolished chamfered edges can scatter light, which causes side mode(s) to be suppressed. However, the claimed subject matter is not so limited.

With reference to <FIG>, illustrated is an exemplary lidar sensor system <NUM>. The lidar sensor system <NUM> can be a frequency modulated continuous wave (FMCW) lidar sensor system; however, the claimed subject matter is not so limited. The lidar sensor system <NUM> includes a laser <NUM>, an optical coupler <NUM>, and a resonator device <NUM>. The optical coupler <NUM> is coupled to the laser <NUM>, and the resonator device <NUM> is coupled to the optical coupler <NUM>. The resonator device <NUM> can be the asymmetric whispering gallery mode resonator device <NUM> of <FIG>, the asymmetric whispering gallery mode resonator device <NUM> of <FIG>, the symmetric whispering gallery mode resonator device <NUM> of <FIG>, or the like.

The laser <NUM> can be a semiconductor laser, a laser diode, or the like. The optical coupler <NUM> can be configured to couple light outputted by the laser <NUM> to the resonator device <NUM>. Further, the optical coupler <NUM> can be configured to couple light returning from the resonator device <NUM> to the laser <NUM>.

As described herein, the resonator device <NUM> can include electrodes to which a voltage can be applied. Application of a voltage to the resonator device <NUM> can change an optical property of an electrooptic material of the resonator device <NUM>. For instance, application of a voltage can change an index of refraction of the electrooptic material of the resonator device <NUM>.

The laser <NUM> is optically injection locked to the resonator device <NUM>. The laser <NUM> can be injection locked to a fundamental mode of the resonator device <NUM>. Further, side mode(s) can be suppressed as described herein. Moreover, since the laser <NUM> is optically injection locked to the resonator device <NUM>, a voltage applied to the resonator device <NUM> can impart a frequency change on the laser <NUM>.

The lidar sensor system <NUM> further includes front end optics <NUM> configured to transmit, into an environment of the lidar sensor system <NUM>, at least a portion of an optical signal generated by the laser <NUM>. According to various examples, the front end optics <NUM> can include a scanner, which can direct the optical signal over a field of view in the environment. The front end optics <NUM> can also include other optical elements, such as one or more lenses, an optical isolator, one or more waveguides, an optical amplifier, an interferometer, and so forth. Such optical elements can enable generating the optical signal with desired properties such as collimation, divergence angle, linewidth, power, and the like. Such optical elements may be assembled discretely, or integrated on a chip, or in a combination of both. The front end optics <NUM> can also be configured to receive a reflected optical signal from the environment. The reflected optical signal can correspond to at least a part of the optical signal transmitted into the environment that reflected off an object in the environment.

Moreover, the lidar sensor system <NUM> can include a detector <NUM> (e.g., a photodetector) and processing circuitry <NUM>. The detector <NUM> can be configured to mix the reflected optical signal received by the front end optics <NUM> with a local oscillator portion of the optical signal generated by the laser <NUM>. The processing circuitry <NUM> can be configured to compute distance and velocity data of the object in the environment based on output of the detector <NUM>.

<FIG> illustrates an exemplary methodology related to manufacturing asymmetric whispering gallery mode resonator devices described herein. While the methodology is shown and described as being a series of acts that are performed in a sequence, it is to be understood and appreciated that the methodology is not limited by the order of the sequence. For example, some acts can occur in a different order than what is described herein. In addition, an act can occur concurrently with another act. Further, in some instances, not all acts may be required to implement the methodology described herein.

<FIG> illustrates a methodology <NUM> of manufacturing an asymmetric whispering gallery mode resonator device. At <NUM>, a first electrode layer can be provided on an electrooptic material layer. At <NUM>, a second electrode layer can be provided on the electrooptic material layer. The electrooptic material layer can include a crystalline material such as calcium fluoride, magnesium fluoride, lithium niobite, lithium tantalate, silicon, or the like. Moreover, the electrode layers can each include a metal such as gold. Moreover, it is contemplated that optical insulator layers and bonding metal layers can be between each of the electrode layers and the electrooptic material layer.

Claim 1:
A resonator device (<NUM>; <NUM>; <NUM>), comprising:
an asymmetric whispering gallery mode resonator disk (<NUM>; <NUM>) formed of a transparent material, the asymmetric whispering gallery mode resonator disk comprising:
an axial surface (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>) along a perimeter of the asymmetric whispering gallery mode resonator disk, wherein a first midplane (<NUM>; <NUM>) passes through the axial surface dividing the axial surface into symmetrical halves;
a top surface (<NUM>; <NUM>);
a bottom surface (<NUM>; <NUM>) substantially parallel to the top surface,
wherein a second midplane (<NUM>; <NUM>) is substantially equidistant between the top surface and the bottom surface, and wherein the first midplane and the second midplane are non-coextensive;
a first chamfered edge (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>) between the top surface and the axial surface; and
a second chamfered edge (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>) between the bottom surface and the axial surface;
a first electrode (<NUM>; <NUM>) on the top surface of the asymmetric whispering gallery mode resonator disk; and
a second electrode (<NUM>; <NUM>) on the bottom surface of the asymmetric whispering gallery mode resonator disk.