Patent Description:
<CIT> discloses an illumination light source provided with a laser light source having a laser medium with a specified gain region, and a reflector having a narrow band reflection characteristic. A part of a laser light emitted from the laser light source is reflected and fed back by the reflector, so that an oscillation wavelength of the laser light source is fixed at a reflection wavelength. A peak of the gain region of the laser medium is shifted from the reflection wavelength by a change of an oscillation characteristic of the laser light source, so that the oscillation wavelength of the laser light source is changed from the reflection wavelength. Thus, an oscillation spectrum of the laser light source is spread to reduce speckle noise.

<CIT> discloses a method of operating a laser source. The method reduces speckle contrast in a projected image by creating a plurality of statistically independent speckle patterns. The method comprises generating a plurality of sub-beams that define an optical mode. The method further comprises controlling the phase of selected sub-beams to continuously sequence the laser source through a plurality of orthogonal optical modes. The plurality of orthogonal modes create a corresponding number of statistically independent speckle patterns, thus reducing speckle contrast in an image projected using the laser source by time averaging.

<CIT> discloses methods for operating a light source of a scanning laser projector to reduce speckle and image flicker in projected images. The methods generally include projecting an image comprising a plurality of frames with a light source of the scanning laser projector. Simultaneously, a speckle reduction sequence comprising uncorrelated speckle patterns and partially correlated speckle patterns is projected with the light source of the scanning laser projector. The speckle reduction sequence is projected by varying a property of an output beam of the light source of the scanning projector. The duration of the speckle reduction sequence may be less than about <NUM> seconds or from about <NUM> seconds to about <NUM> seconds.

<CIT> discloses an eye-tracking system that includes a light source configured to emit at least infrared (IR) light and a microelectromechanical system (MEMS) scanning mirror configured to direct the IR light. The system further includes a relay including at least one prism, and the relay is configured to receive the IR light directed by the MEMS scanning mirror and redirect the IR light. The system further includes a waveguide through which the IR light redirected by the relay passes to reach an eye, and at least one sensor configured to receive the IR light after being reflected by the eye.

<CIT>) discloses techniques for reducing interference caused by spatial coherence within a waveguide in a near eye display, NED. NED devices can include coherent light sources (e.g., laser scanners) to achieve a larger field of view and/or better resolution than conventional LED sources. Due to the nature of the coherent light source, the coherent light rays, which are diffracted in a waveguide of a NED device, can overlap and interfere with each other.

To reduce the interference, an NED device according to the technique can include a spatial light modulator (SLM) to modulate phases of the light rays so that light rays after modulation are no longer coherent with each other and therefore do not interfere within the waveguide.

<CIT> discloses a widely tunable multi-mode semiconductor laser containing only two electrically active sections, being an optical gain section and a tunable distributed Bragg reflector section adapted to reflect at a plurality of wavelengths, wherein the gain section is bounded by the tunable distributed Bragg reflector section and a broadband facet reflector, and wherein the tunable distributed Bragg reflector section comprises a plurality of discrete segments capable of being selectively tuned, wherein the reflection spectra of one or more segments of the tunable distributed Bragg reflector section can be tuned lower in wavelength to reflect with the reflection spectrum of a further segment of the tunable distributed Bragg reflector section to provide a wavelength range of enhanced reflectivity.

An edge-emitting laser includes an active gain section and a reflector section optically coupled to the active gain section. The active gain section is configured to amplify an optical power of light across a wavelength range. The reflector section is configured to selectively reflect light of a selected wavelength within the wavelength range. The selected wavelength is tunable via high-frequency index modulation of the reflector section. The active gain section and the reflector section collectively form an optical cavity configured to lase coherent light in the selected wavelength.

Compared to other common light sources such as light emitting diodes (LEDs) which work based on a light emission process called spontaneous emission, lasers produce light through stimulated emission. Stimulated emission copies existing photons in an optical cavity, and each copy has the same wavelength as the original. This process results in a narrower spectral bandwidth in lasers compared to LEDs and other light sources that produce light based on spontaneous emission.

Having narrower spectra in lasers causes several challenges in display applications. As one example, a narrow spectral bandwidth may cause high-contrast fringe artifacts in waveguide-based displays. Fringes are formed in waveguide-based displays due to a multitude of possible interactions between coherent laser beams with different optical path lengths. As another example, a laser-based display may present a sharp contrast in the field of view (FOV) boundaries or in the boundaries between different waveguide plates. For a natural user experience, it is preferred that these boundaries are indistinct from their surroundings.

Accordingly, the present disclosure is directed to an edge-emitting laser configured to lase coherent light in a selected wavelength that is tunable within a wavelength range. The selected wavelength may be modulated at a suitably high frequency to broaden the perceived bandwidth of light output from the edge-emitting laser. In one example, the edge-emitting laser includes an active gain section and a reflector section optically coupled to the active gain section. The active gain section is configured to amplify an optical power of light across a wavelength range. The reflector section is configured to selectively reflect light of a selected wavelength within the wavelength range. The selected wavelength is tunable via high-frequency index modulation of the reflector section. The active gain section and the reflector section collectively form an optical cavity configured to lase coherent light in the selected wavelength.

Such an edge-emitting laser may have a perceived spectral bandwidth that is broader than a typical narrow-band laser. Returning to the example of the waveguide-based display discussed above, by using a laser having an increased laser bandwidth, a larger number of wavelengths in the laser spectrum may interfere and the superposition of all the wavelengths results in the washout of the contrast in the interference fringes. In this way, the edge-emitting laser may reduce perception of fringe interference artifacts in images presented by such a waveguide-based display. Turning to the high-contrast boundary issue discussed above, by using a laser having an increased laser bandwidth, light inside the waveguide may couple out at a larger range of angles causing overlap of different wavelengths that blur out the FOV boundaries. In this way, the edge-emitting laser may improve the image quality of images presented by such a waveguide-based display.

<FIG> shows aspects of an example implementation environment for a near-eye display system <NUM>. As illustrated herein, near-eye display system <NUM> is a component of a head-mounted electronic device <NUM>, which is worn and operated by a user <NUM>. The near-eye display system <NUM> is configured to present virtual imagery in the user's field of view. In some implementations, user-input componentry of the wearable electronic device <NUM> may enable the user to interact with the virtual imagery. The wearable electronic device <NUM> takes the form of eyeglasses in the example of <FIG>. In other examples, the wearable electronic device <NUM> may take the form of goggles, a helmet, or a visor. In still other examples, the near-eye display system <NUM> may be a component of a non-wearable electronic device, such as a heads-up display.

The near-eye display system <NUM> may be configured to cover one or both eyes of the user <NUM> and may be adapted for monocular or binocular image display. In examples in which the near-eye display system <NUM> covers only one eye, but binocular image display is desired, a complementary near-eye display system may be arranged over the other eye. In examples in which the near-eye display system covers both eyes and binocular image display is desired, the virtual imagery presented by near-eye display system <NUM> may be divided into right and left portions directed to the right and left eyes, respectively. In scenarios in which stereoscopic image display is desired, the virtual imagery from the right and left portions, or complementary near-eye display systems, may be configured with appropriate stereo disparity so as to present a three-dimensional subject or scene.

<FIG> shows an example of the near-eye display system <NUM> that uses a laser assembly <NUM> as an illumination source. The laser assembly <NUM> includes lasers 202A (e.g., a red laser), 202B (e.g., a green laser), and 202C (e.g., a blue laser). Although only three lasers are shown, it will be appreciated that the laser assembly <NUM> may include any suitable number of lasers. For example, the laser assembly <NUM> may include <NUM>, <NUM>, <NUM>, <NUM>, or more than <NUM> red lasers; <NUM>, <NUM>, <NUM>, <NUM>, or more than <NUM> green lasers; <NUM>, <NUM>, <NUM>, <NUM>, or more than <NUM> blue lasers; and <NUM>, <NUM>, <NUM>, <NUM>, or more than <NUM> lasers of other colors. Any combination or modification in the number of lasers may also be available (e.g., <NUM> red, <NUM> green, <NUM> blue, or <NUM> red, <NUM> green, <NUM> blue, etc.). Accordingly, any number of lasers may be used to irradiate/illuminate pixels for generating image content.

In some instances (though not all), the laser assembly <NUM> also includes a collimating lens assembly <NUM> (or other diffractive optical element) that is structured to direct light to another location or otherwise operate on the light in some manner. In this example, each of the lasers 202A, 202B, and 202C has a corresponding collimating lens 204A, 204B, 204C. In some implementations, however, a single collimating lens may be used for more than one laser.

The near-eye display <NUM> includes combination optics <NUM> configured to spatially combine the light beams lased from the plurality of lasers 202A, 202B, and 202C into a single light beam.

The near-eye display system <NUM> includes a micro-electro-mechanical mirror system (MEMs) <NUM>, though the principles disclosed herein are applicable to any type of laser-based display unit and not only to architectures with the MEMs <NUM>. The MEMs <NUM> is configured to collect laser light from the combination optics <NUM>, which combines light lased from three different sources (i.e. the lasers 202A, 202B, and 202C). Additionally, the MEMs <NUM> is configured to direct laser light 208A (which, in this example includes red laser light, green laser light, and blue laser light) to a waveguide <NUM>. Furthermore, the MEMs <NUM> is configured to redirect its mirrors/mirror array so that the laser light 208A is aimed at different locations at the waveguide <NUM>. As shown, laser lights 208B and 208C are aimed at different locations on the waveguide <NUM>. In this manner, the MEMs <NUM> is able to route light to different locations by adjusting the aim of its corresponding mirror array. It will be appreciated that the laser lights 208A-C may be modulated to include varying degrees or intensities (or even an absence of any one or more) of red, green, blue, or other color laser light.

The waveguide <NUM> is configured to redirect or propagate the laser light 208A-C to a desired location which is viewable by a user's eye <NUM>. It will be appreciated that waveguide <NUM> may be any type of waveguide display (e.g., a surface relief grating waveguide).

The laser light 208A-C enters the waveguide <NUM> via an entry grating <NUM>. The laser light 208A-C then propagates (e.g., via total internal reflection) through the waveguide <NUM> until it reaches an exit grating <NUM>. It will be appreciated that the angles with which the laser light 208A-C enters the waveguide <NUM> are preserved as the laser light 208A-C propagates through the waveguide <NUM>. This condition is shown by the different angles that each of the respective laser lights 208A-C propagate through the waveguide <NUM>. By configuring the entry grating <NUM> and the exit grating <NUM> to meet certain design parameters, the MEMs <NUM> is able to use waveguide <NUM> to propagate light towards the user's eye <NUM>.

The laser assembly <NUM> and the MEMs <NUM> may be controlled by a controller <NUM>. The controller <NUM> may be configured to control the MEMs <NUM>, in conjunction with the laser assembly <NUM> to progressively scan a set of pixels <NUM> to a target display area for a user's eye <NUM> to view (e.g., by adjusting the mirror array so that the combined RGB laser beam or light is aimed at different locations) individual pixels of that image in such a rapid manner that the entirety of the image appears before the user's eye <NUM> without the user realizing that the image was progressively scanned pixel by pixel and line by line. In this way, the near-eye display system <NUM> may project or render image content for a user to view.

The MEMs <NUM> may be able to scan an image (i.e., pixels of that image) at any image resolution or range of image resolutions (e.g., in cases where foveated rendering is used). For example, in some implementations, the MEMs <NUM> is configured to scan RGB light from the laser assembly <NUM> with a resolution of <NUM>,<NUM> pixels by <NUM>,<NUM> pixels, or any other resolution.

There are various instances in which, due to the wave properties of laser light, fringe interference can occur based on coherent light output from a laser assembly propagating through a waveguide (e.g., waveguide <NUM> shown in <FIG>). As a result of such fringe interference, various different artifacts including bright and dark rings/spots may be created in an image output from the waveguide. <FIG> shows an example image <NUM> including artifacts <NUM> and <NUM> caused by such fringe interference. The artifacts <NUM>, <NUM> include irregularities in terms of brightness. The presence of such artifacts in an image can lower the perceived quality of the image and thereby negatively affect the user experience. In the depicted example, the artifact <NUM> distorts the appearance of a dragon in the image <NUM>. Further, the artifact <NUM> distorts the appearance of a fireball shot by a wizard at the dragon in the image <NUM>.

In order to reduce fringe interference that creates artifacts in an image output from the waveguide, a laser assembly may be configured to lase coherent light in a selected wavelength. The selected wavelength is rapidly tunable within a wavelength range via high-frequency modulation such that the laser may have a perceived increased bandwidth. By using a laser having an increased perceived laser bandwidth, a larger number of wavelengths in the laser spectrum may interfere and the superposition of all the wavelengths may result in washing out the contrast of the fringe interference.

<FIG> schematically shows an example laser assembly <NUM> configured to lase coherent light in a selected wavelength that is tunable within a wavelength range. The laser assembly <NUM> may be representative of any of the lasers 202A, 202B, 202C included in the near-eye display system <NUM> shown in <FIG>. The laser assembly <NUM> includes an optical cavity <NUM> positioned on a substrate <NUM>. The optical cavity 401includes an active gain section <NUM> and a reflector <NUM> section. The active gain section <NUM> may be optically coupled to the reflector section <NUM> via a transmissive interface <NUM>. In the depicted example, the active gain section <NUM> is edge coupled to the reflector section <NUM> via the transmissive interface <NUM>. The transmissive interface <NUM> may be any suitable interface between the two sections of the optical cavity <NUM> that supports low coupling loss. It will be appreciated that the active gain section <NUM> may be optically coupled to the reflector section <NUM> in any suitable manner.

The active gain section <NUM> is the source of optical gain within the laser assembly <NUM>. The active gain section <NUM> is configured to amplify an optical power of light reflecting within the optical cavity across a wavelength range. The gain/amplification results from the stimulated emission of electronic or molecular transitions of an active gain medium of the active gain section <NUM> to a lower energy state from a higher energy state previously populated by a pump source. Laser pumping of the active gain section <NUM> may be performed using different pump sources, such as electrical currents or light generated by discharge lamps or by other lasers, for example. In one particular example, the active gain section <NUM> is configured as a reflective semiconductor optical amplifier (RSOA).

The reflector section <NUM> may be configured to selectively reflect light of a selected wavelength within a wavelength range. The reflector section <NUM> may include a grating-based filter <NUM> to facilitate selective reflection across the wavelength range. The reflector section <NUM> may include any suitable grating-based filter. In one example, the grating-based filter <NUM> is a Distributed Bragg Grating (DBG). The DBG may be formed from multiple layers of alternating materials with varying refractive index, or by periodic variation of some characteristic (such as height) of a dielectric waveguide, resulting in periodic variation in the effective refractive index of the DBG. Each layer boundary causes a partial reflection of an optical wave. These partial reflections combine with constructive interference, such that the layers of the DBG act as a high-quality reflector. The DBG may be configured to reflect any suitable range of wavelengths.

Furthermore, the reflector section <NUM> may include electro-optic material <NUM> that is configured to modulate a reflective index of the reflector section <NUM> as a function of a voltage of a waveform applied to the electro-optic material <NUM>. In particular, as a voltage of a waveform applied to the electro-optic material <NUM> varies, the refractive index of the electro-optic material changes under the grating-based filter <NUM> which shifts the resonant frequency of the grating-based filter <NUM> to reflect different selected wavelengths of light within the wavelength range of the grating-based filter <NUM>. The reflector section <NUM> may include any suitable electro-optic material. Non-limiting examples include crystalline electro-optic materials, polymer electro-optic materials, and organic electro-optic materials.

The active gain section <NUM> includes a selectively reflective end <NUM>. The reflector section <NUM> and the reflective end <NUM> may allow coherent light of a selected wavelength to reflect back and forth within the optical cavity. Each time a light beam passes through the active gain section, the optical power of the light beam may be amplified. The selectively reflective end <NUM> may be partially transparent to allow coherent light <NUM> to be output from the optical cavity <NUM>.

The optical cavity <NUM> has an overall length (L). In some implementations, the overall length (L) of the optical cavity <NUM> may satisfy fringe mitigation requirements while the power consumption is determined mainly by a length (LA) of the active gain section <NUM>. The length (LA) of the active gain section <NUM> may be determined based on the laser requirement for the particular application. A length (LR) of the reflector section <NUM> can be selected, given a particular active section length, to provide an overall length (L) that avoids fringe optical path lengths (OPLs) that are imposed by a corresponding waveguide into which the laser assembly <NUM> lases coherent light. The length (LA) of the active gain section <NUM>, the length (LR) of the reflector section <NUM>, and/or the length (L) of the optical cavity <NUM> may be any suitable length.

A controller <NUM> is electrically connected to the active gain section <NUM> and the reflector section <NUM>. The controller <NUM> may be configured to control the laser assembly <NUM> to selectively lase coherent light in a selected wavelength within the wavelength range. In particular, the controller <NUM> may be configured to selectively apply a current to the active gain section <NUM> to cause the active gain section <NUM> to amplify the optical power of light in the optical cavity <NUM>. The controller <NUM> may be further configured to modulate a voltage of a waveform applied to the reflector section <NUM> to tune the reflector section <NUM> to reflect a selected wavelength of coherent light such that coherent light in the selected wavelength may be lased from the optical cavity <NUM>.

The controller <NUM> may be configured to adjust the voltage to change the selected wavelength of coherent light lased by the optical cavity <NUM>. <FIG> depicts an example gain spectrum <NUM> of the active gain section <NUM> and an example reflector loss spectrum <NUM> of the reflector section <NUM>. The gain spectrum <NUM> includes a plurality of different wavelengths (e.g., λ<NUM>, λ<NUM>, λ<NUM>) at different mode locations within the gain spectrum <NUM>. The heights of the different wavelengths in the gain spectrum <NUM> indicate an optical gain of light in that wavelength amplified by the active gain section <NUM>. The reflector loss spectrum <NUM> includes a plurality of different wavelengths to which the reflector section <NUM> may be tuned to reflect light based on a corresponding voltage (e.g., V<NUM>, V<NUM>, V<NUM>) being applied to the reflector section <NUM> by the controller <NUM>. For example, the controller <NUM> may apply voltage Vl to the reflector section <NUM> to tune the reflector section <NUM> to reflect light having a wavelength λ<NUM>. The controller <NUM> may apply voltage V<NUM> to the reflector section <NUM> to tune the reflector section <NUM> to reflect light having a wavelength λ<NUM>. The controller <NUM> may apply voltage V<NUM> to the reflector section <NUM> to tune the reflector section <NUM> to reflect light having a wavelength λ<NUM>. The reflector section <NUM> may be tuned such that a selected wavelength has a minimum loss (i.e., is reflected), and the gain at the selected wavelength becomes greater than the loss such that light at the selected wavelength is lased from the optical cavity <NUM>.

The controller <NUM> may be configured to modulate the refractive index of the reflector section <NUM> to reflect light at different wavelengths at a relatively high frequency. As one example, the controller <NUM> may be configured to switch the reflector section <NUM> between different wavelengths with a high enough frequency that the effective spectrum of coherent light lased from the laser assembly <NUM> would have a perceived bandwidth that is wider than any of the individual wavelengths. For example, as shown in <FIG>, the controller <NUM> may be configured to modulate the voltage of a waveform applied to the reflector section <NUM> to rapidly switch between reflecting light having wavelengths λ<NUM>, λ<NUM>, and λ<NUM>. The controller <NUM> may be configured to modulate the voltage of a waveform applied to the reflector section <NUM> at a frequency suitably high enough to produce a time averaged lasing spectrum <NUM> of the plurality of different lasing spectra with a perceived bandwidth that is substantially wider than each of the individual spectra corresponding to λ<NUM>, λ<NUM>, and λ<NUM>.

The controller <NUM> may be configured to modulate the reflector section <NUM> to switch between reflecting light at different wavelengths at any suitable frequency. In one example where the laser assembly <NUM> is configured to lase coherent light to a display including a plurality of pixels (e.g., near-eye display system <NUM> shown in <FIG>), the controller <NUM> may be configured to modulate the voltage of a waveform applied to the reflector section <NUM> at least on a per pixel basis (e.g., rapidly switch between different wavelengths in less than one pixel time) for each of the plurality of pixels of the display. <FIG> show an example reflector modulation voltage drive scheme in which the controller <NUM> periodically modulates the voltage of a waveform applied to the reflector section <NUM> over two periods. In one example, a period is equivalent to twice a pixel time at which a pixel is scanned for a display (e.g., ~<NUM> nanoseconds). In each period (e.g., P1, P2), the voltage is modulated as a triangle wave from a high voltage to a low voltage and back to the high voltage. <FIG> shows corresponding laser wavelength modulation over two periods based on the reflector modulation voltage drive scheme shown in <FIG>. The high voltage in the drive scheme corresponds to selecting a lasing central wavelength λ<NUM> and the low voltage corresponds to selecting a lasing central wavelength λ<NUM>. According to such a drive scheme, the lasing central wavelength can be modulated to have a perceived bandwidth between λ<NUM> and λ<NUM> which may be wider than any single wavelength spectra. In the depicted example, the central wavelength is sinusoidally modulated. In other examples, the central wavelength may be differently modulated. Using the example of <FIG>, in P1 the lasing central wavelength is modulated from λ<NUM> to λ<NUM> to have a perceived bandwidth between λ<NUM> and λ<NUM> for a first pixel. Then, still in P1, the lasing central wavelength is modulated from λ<NUM> to λ<NUM> to have a perceived bandwidth between λ<NUM> and λ<NUM> for a second pixel. In P2, the lasing central wavelength is modulated from λ<NUM> to λ<NUM> to have a perceived bandwidth between λ<NUM> and λ<NUM> for a third pixel. Then, still in P2, the lasing central wavelength is modulated from λ<NUM> to λ<NUM> to have a perceived bandwidth between λ<NUM> and λ<NUM> for a fourth pixel.

Increasing the perceived laser bandwidth may address a variety of issues for a laser-based display. For example, increasing the laser bandwidth via high-frequency modulation may cause a large number of wavelengths in the laser spectrum to interfere and the superposition of all the wavelengths may result in a washout of contrast for interference fringes. In this way, fringe interference artifacts in images presented by such a laser-based display may be reduced. As another example, increasing the laser bandwidth may cause light inside a waveguide to couple out at a larger range of angles causing overlap of different wavelengths that blur out FOV boundaries. In this way, image quality of images presented by such a laser-based display may be improved.

<FIG> shows an example method <NUM> for operating an edge-emitting laser, such as the laser assemblies <NUM> and <NUM> shown in <FIG> and <FIG>. For example, the method <NUM> may be performed by the near-eye display system <NUM> shown in <FIG>, and/or the controller <NUM> shown in <FIG>. At <NUM>, the method <NUM> includes applying a waveform having a first voltage to a reflector section of an optical cavity of the edge-emitting laser to tune the reflector section to reflect coherent light having a first wavelength. The reflector section may be configured to selectively reflect light of a selected wavelength, wherein the selected wavelength is tunable via high-frequency index modulation of the reflector section. At <NUM>, the method <NUM> includes exciting an active gain section of the optical cavity of the edge-emitting laser to lase coherent light having the first wavelength. At <NUM>, the method <NUM> includes applying a waveform having a second voltage, different than the first voltage, to the reflector section to tune the reflector section to reflect coherent light having a second wavelength different than the first wavelength. At <NUM>, the method <NUM> includes exciting the active gain section to lase coherent light having the second wavelength.

In some implementations, the method <NUM> may be repeatedly performed. In some implementations, the method <NUM> may be repeatedly performed at a frequency suitably high enough to widen a perceived bandwidth of the coherent light lased from the edge-emitting laser. In some implementations wherein the edge-emitting laser is configured to lase the coherent light to a display including a plurality of pixels, the method <NUM> may be repeatedly performed at a frequency that is at least on a per pixel basis to lase coherent light to each of the plurality of pixels of the display.

<FIG> schematically shows a simplified representation of a computing system <NUM> configured to provide any to all of the compute functionality described herein. Computing system <NUM> may take the form of one or more head-mounted, near-eye display devices, personal computers, network-accessible server computers, tablet computers, home-entertainment computers, gaming devices, mobile computing devices, mobile communication devices (e.g., smart phone), virtual/augmented/mixed reality computing devices, wearable computing devices, Internet of Things (IoT) devices, embedded computing devices, and/or other computing devices. For example, computing system <NUM> may be representative of the head-mounted electronic device <NUM> in <FIG>.

Computing system <NUM> includes a logic subsystem <NUM> and a storage subsystem <NUM> Computing system <NUM> may optionally include a display subsystem <NUM>, input subsystem <NUM>, communication subsystem <NUM>, and/or other subsystems not shown in <FIG>.

Logic subsystem <NUM> includes one or more physical devices configured to execute instructions. For example, the logic subsystem <NUM> may be configured to execute instructions that are part of one or more applications, services, or other logical constructs. The logic subsystem <NUM> may include one or more hardware processors configured to execute software instructions. Additionally or alternatively, the logic subsystem <NUM> may include one or more hardware or firmware devices configured to execute hardware or firmware instructions. Processors of the logic subsystem <NUM> may be single-core or multicore, and the instructions executed thereon may be configured for sequential, parallel, and/or distributed processing. Individual components of the logic subsystem <NUM> optionally may be distributed among two or more separate devices, which may be remotely located and/or configured for coordinated processing. Aspects of the logic subsystem <NUM> may be virtualized and executed by remotely-accessible, networked computing devices configured in a cloud-computing configuration.

Storage subsystem <NUM> includes one or more physical devices configured to temporarily and/or permanently hold computer information such as data and instructions executable by the logic subsystem <NUM>. When the storage subsystem <NUM> includes two or more devices, the devices may be collocated and/or remotely located. Storage subsystem <NUM> may include volatile, nonvolatile, dynamic, static, read/write, read-only, random-access, sequential-access, location-addressable, file-addressable, and/or content-addressable devices. Storage subsystem <NUM> may include removable and/or built-in devices. When the logic subsystem <NUM> executes instructions, the state of storage subsystem <NUM> may be transformed - e.g., to hold different data.

The logic subsystem <NUM> and the storage subsystem <NUM> may cooperate to instantiate one or more logic machines. As used herein, the term "machine" is used to collectively refer to the combination of hardware, firmware, software, instructions, and/or any other components cooperating to provide computer functionality. In other words, "machines" are never abstract ideas and always have a tangible form. A machine may be instantiated by a single computing device, or a machine may include two or more subcomponents instantiated by two or more different computing devices. In some implementations a machine includes a local component (e.g., software application executed by a computer processor) cooperating with a remote component (e.g., cloud computing service provided by a network of server computers). The software and/or other instructions that give a particular machine its functionality may optionally be saved as one or more unexecuted modules on one or more suitable storage devices. As examples, the logic subsystem <NUM> and the storage subsystem <NUM> may be implemented as a controller, such as controller <NUM> shown in <FIG> and <FIG>.

When included, display subsystem <NUM> may be used to present a visual representation of data held by storage subsystem <NUM>. In some implementations, display subsystem may include one or more virtual-, augmented-, or mixed reality displays. As an example, display subsystem <NUM> may be implemented as the near-eye display system <NUM> shown in <FIG> and/or the near-eye display system <NUM> shown in <FIG>.

When included, input subsystem <NUM> may comprise or interface with one or more input devices. An input device may include a sensor device or a user input device. Examples of user input devices include a keyboard, mouse, touch screen, or game controller. Example NUI componentry may include a microphone for speech and/or voice recognition; an infrared, color, stereoscopic, and/or depth camera for machine vision and/or gesture recognition; a head tracker, eye tracker, accelerometer, and/or gyroscope for motion detection and/or intent recognition.

The communication subsystem <NUM> may be configured for communication via personal-, local- and/or wide-area networks.

In an example, edge-emitting laser comprises an active gain section configured to amplify an optical power of light across a wavelength range, and a reflector section optically coupled to the active gain section and configured to selectively reflect light of a selected wavelength within the wavelength range, wherein the selected wavelength is tunable via high-frequency index modulation of the reflector section, wherein the active gain section and the reflector section collectively form an optical cavity configured to lase coherent light in the selected wavelength. In this example and/or other examples, the reflector section may include a grating-based filter. In this example and/or other examples, the grating-based filter may be a Distributed Bragg Reflector. In this example and/or other examples, the reflector section may include electro-optic material configured to modulate a reflective index of the reflector section as a function of a voltage of a waveform applied to the electro-optic material. In this example and/or other examples, the edge-emitting laser may further comprise a controller configured to modulate a voltage of a waveform applied to the reflector section to tune the selected wavelength of the coherent light lased by the optical cavity. In this example and/or other examples, the controller may be configured to periodically modulate the voltage of the waveform applied to the reflector section. In this example and/or other examples, the controller may be configured to modulate the voltage of the waveform applied to the reflector section to sinusoidally modulate the selected wavelength within the wavelength range. In this example and/or other examples, the edge-emitting laser may be configured to lase the coherent light to a display including a plurality of pixels, and the controller may be configured to modulate the voltage of the waveform applied to the reflector section at least on a per pixel basis for the plurality of pixels of the display. In this example and/or other examples, the controller may be configured to modulate the voltage of the waveform applied to the reflector section at a frequency suitably high enough to widen a perceived bandwidth of the coherent light. In this example and/or other examples, the edge-emitting laser may be configured to lase coherent light into a waveguide, and the controller may be configured to tune the perceived bandwidth of the coherent light to reduce fringe interference due to the coherent light propagating through the waveguide.

In an example, an edge-emitting laser comprises an active gain section configured to amplify an optical power of light across a wavelength range, and a reflector section optically coupled to the active gain section and configured to selectively reflect light of a selected wavelength within the wavelength range, wherein the selected wavelength is tunable via high-frequency index modulation of the reflector section, wherein the active gain section and the reflector section collectively form an optical cavity configured to lase coherent light in the selected wavelength, and a controller configured to modulate a voltage of a waveform applied to the reflector section to tune the selected wavelength of the coherent light lased by the optical cavity. In this example and/or other examples, the controller may be configured to periodically modulate the voltage of the waveform applied to the reflector section. In this example and/or other examples, the controller may be configured to modulate the voltage of the waveform applied to the reflector section to sinusoidally modulate the selected wavelength within the wavelength range. In this example and/or other examples, the edge-emitting laser may be configured to lase the coherent light to a display including a plurality of pixels, and the controller may be configured to modulate the voltage of the waveform applied to the reflector section at least on a per pixel basis for the plurality of pixels of the display. In this example and/or other examples, the controller may be configured to modulate the voltage of the waveform applied to the reflector section at a frequency suitably high enough to widen a perceived bandwidth of the coherent light. In this example and/or other examples, the edge-emitting laser may be configured to lase coherent light into a waveguide, and the controller may be configured to tune a perceived bandwidth of the coherent light to reduce fringe interference due to the coherent light propagating through the waveguide.

In an example, a method for operating an edge-emitting laser having an optical cavity including an active gain section and a reflector section configured to selectively reflect light of a selected wavelength tunable via high-frequency index modulation of the reflector section, comprises applying a waveform having a first voltage to the reflector section to tune the reflector section to reflect coherent light having a first wavelength, exciting the active gain section to lase coherent light having the first wavelength, applying a waveform having a second voltage, different than the first voltage, to the reflector section to tune the reflector section to reflect coherent light having a second wavelength different than the first wavelength, and exciting the active gain section to lase coherent light having the second wavelength. In this example and/or other examples, the reflector section may be tuned periodically between reflecting coherent light having the first wavelength and reflecting coherent light having the second wavelength. In this example and/or other examples, the reflector section may be tuned between reflecting coherent light having the first wavelength and reflecting coherent light having the second wavelength at a frequency suitably high enough to widen a perceived bandwidth of the coherent light. In this example and/or other examples, the edge-emitting laser may be configured to lase the coherent light to a display including a plurality of pixels, and the reflector section may be tuned between reflecting coherent light having the first wavelength and reflecting coherent light having the second wavelength at least on a per pixel basis for the plurality of pixels of the display.

Claim 1:
An edge-emitting laser (<NUM>; <NUM>) connectable to a waveguide (<NUM>) and to a display including a plurality of pixels (<NUM>), the edge-emitting laser (<NUM>) comprising:
an active gain section (<NUM>) configured to amplify an optical power of light across a wavelength range;
a reflector section (<NUM>) optically coupled to the active gain section (<NUM>) and configured to selectively reflect light of a selected wavelength within the wavelength range, wherein the selected wavelength is tunable via high-frequency index modulation of the reflector section (<NUM>),
wherein the active gain section (<NUM>) and the reflector section (<NUM>) collectively form an optical cavity (<NUM>) configured to lase coherent light in the selected wavelength into the waveguide (<NUM>) and to the display; and
a controller (<NUM>) configured to modulate a voltage of a waveform applied to the reflector section (<NUM>) to tune the selected wavelength of the coherent light lased by the optical cavity (<NUM>) between a plurality of different lasing spectra at a frequency to produce a time average lasing spectrum (<NUM>) of the plurality of different lasing spectra at each pixel (<NUM>) with a bandwidth that is wider than each of the individual different lasing spectra such that fringe interference due to the coherent light propagating through the waveguide (<NUM>) is reduced.