Integrated Photonics Air Data System

Abstract

To provide an integrated photonics air data system.SOLUTION: A light beam from a laser source 104 is routed to multiple tunable optical filters 106 operative to transmit the light beam to one of multiple emitting grating couplers at any given time. The tunable optical filters are configured such that the light beam is emitted into a region of interest at different times from each of the emitting grating couplers. A passive optical filter array is configured to receive scattered light from the emitted light beam. The passive optical filter array comprises multiple optical notch filters in optical communication with each other and operative for frequency selection, and multiple optical detectors 108 each coupled to an output of one of the optical notch filters. The passive optical filter array is operative to perform frequency spectrum decomposition of the received scattered light into multiple signals.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001] Optical detection systems, such as light detection and ranging (lidar) systems, are useful for analyzing air data in the surrounding environment. Often, these lidar systems are implemented in vehicles, such as aircraft, and are useful for converting air data measurements into various air data parameters that can assist the vehicle operator as the vehicle moves and navigates.

[0002] Lidar systems operate by emitting light beams outward from the vehicle at various target areas. When the emitted light beams collide with anomalies in the environment, the light is scattered consistently with the principles of Mie and Rayleigh scattering. The backscattered light can then be detected by the Lidar system, and the difference (e.g., frequency shift) between the emitted light and the backscattered light can be analyzed to determine relevant information about the surrounding environment. Summary of the Invention

[0003] In one embodiment, an integrated photonics chip is provided. The integrated photonics chip includes a photonics substrate and a laser source operably coupled to the photonics substrate. The laser source is operative to emit a light beam. The integrated photonics chip further includes a plurality of tunable optical filters on the photonics substrate, where the tunable optical filters are in optical communication with each other and with the laser source. The integrated photonics chip further includes a plurality of emission grating couplers on the photonics substrate, each emission grating coupler coupled to an output of one of the tunable optical filters. Each emission grating coupler is configured to emit a light beam received from the output of its respective tunable optical filter into a target region in a different direction. The integrated photonics chip further includes at least one receiver grating coupler on the photonics substrate, where the receiver grating coupler is configured to receive scattered light from the target region. The integrated photonics chip further comprises a passive optical filter array on the photonics substrate in optical communication with the receiving grating coupler. The passive optical filter array is configured to receive scattered light from the receiving grating coupler. The passive optical filter array comprises a plurality of optical notch filters operative for frequency selection and a plurality of optical detectors, each optical detector coupled to an output of one of the optical notch filters. Each of the optical notch filters is configured to pass the received scattered light in a corresponding wavelength range to a respective one of the optical detectors, where each corresponding wavelength range is distinct. The passive optical filter array operates to perform frequency spectral decomposition of the received scattered light into a plurality of signals. The light beam emitted from the laser source is sent to one or more tunable optical filters operative to enable transmission of the light beam to one of the emission grating couplers at any given time, such that the light beam is emitted from each of the emission grating couplers into the region of interest at different times. [Brief explanation of the drawings]

[0004] Exemplary features of the present disclosure, its nature, and various advantages will become apparent from the accompanying drawings and the following detailed description of various embodiments. Non-limiting and non-exhaustive embodiments are described with reference to the accompanying drawings, in which like labels or reference numbers refer to like parts throughout the various drawings unless otherwise specified. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements have been selected, enlarged, and arranged to improve the readability of the drawings. The particular shapes of the depicted elements have been selected for ease of recognition in the drawings. One or more embodiments are described below with reference to the accompanying drawings.

[0005] [Figure 1] FIG. 1 is a schematic perspective view of an optical air data system configured to measure air data parameters based on emitted signals, as described in one or more embodiments.

[0006] [Figure 2] FIG. 1 is a schematic top view of an optical air data system including multiple tunable optical filters and an optical filter array, as described in one or more embodiments.

[0007] [Figure 3] FIG. 1 illustrates the voltage output over time of three tunable optical filters as described in one or more embodiments.

[0008] [Figure 4] 1 is a graph illustrating signal strength per frequency of a received backscattered signal, as described in one or more embodiments.

[0009] [Figure 5A] FIG. 1 is a schematic perspective view of an optical notch filter as described in one or more embodiments.

[0010] [Figure 5B] FIG. 5B is an enlarged top view of a portion of the optical notch filter of FIG. 5A.

[0011] [Figure 5C] 5B is a graph showing the normalized power per wavelength of the signal output by the optical notch filter of FIG. 5A.

[0012] [Figure 6A] FIG. 1 is a cross-sectional side view of a grating coupler that can be implemented as part of an air data system according to an exemplary embodiment.

[0013] [Figure 6B] 6B is a modeled graphical representation of the simulated performance of the grating coupler of FIG. 6A.

[0014] [Figure 7] 1 is a flowchart illustrating a method for determining air data parameters based on emitted signals, as described in one or more embodiments.

[0015] According to common practice, the various features described are not drawn to scale but rather to emphasize particular features relevant to the exemplary embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0016] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific exemplary embodiments. It is to be understood, however, that other embodiments may be utilized and that logical, mechanical, and electrical changes may be made. Furthermore, the methods presented in the drawings and specification should not be construed as limiting the order in which individual steps may be performed. Accordingly, the following detailed description is not to be construed in a limiting sense.

[0017] Traditional air data systems suffer from cumbersome configurations that can unnecessarily increase the power, size, and weight impact of these systems. For example, in a typical light detection and ranging (lidar) system, at least three laser beams in different directions are emitted within a target area to extract air data information. While a multiple laser solution achieves the desired result of emitting multiple light beams, it can also require significant power consumption to maintain laser activity. Additionally, many traditional lidar systems employ discrete optical components with large spatial dimensions that can span the entire vehicle. This can be costly. Not only do such systems require significant cost burdens to maintain, but they can also be impractical or impossible to implement on smaller or more sensitive vehicles, such as urban air traffic control (UAM) vehicles.

[0018] The embodiments described herein address these issues through an improved optical air data system for determining air data parameters for vehicles. Air data systems that can be implemented on microchips can achieve reduced size, weight, power, and cost when compared to traditional lidar-based systems. Additionally, the miniaturization of the described air data systems enables implementation on large and small vehicle aircraft, such as large commercial aircraft, as well as smaller aircraft (e.g., UAM vehicles).

[0019] An exemplary embodiment of an optical air data system includes a light emitting system, such as a laser, configured to transmit a time-division multiplexed signal (e.g., a light beam) to a plurality of tunable optical filters. The tunable optical filters are configured so that the light beam passes through only one tunable optical filter at a time. This may be achieved via a switch coupled to the tunable optical filter that steers the resonant frequency of the tunable optical filter to match the frequency of the laser for a specified time interval. Time-multiplexing the light beam from a single laser allows for reduced power and cost of utilizing an air data system. In another embodiment, the light emitting system comprises a light detection and ranging (lidar) system.

[0020] Additionally, certain embodiments utilize a passive optical filter array comprising multiple notch filters to extract and process backscattered light received from a light beam transmitted into free space. Each of the notch filters is configured to pass a portion of the received optical spectrum. The non-passed spectral portions are cascaded through the optical filter array until they reach a notch filter configured to pass their respective spectral portions. Thus, the optical filter array decomposes the received optical spectrum into organized spectral portions based on frequency or wavelength, which can then be transmitted to a processing system to determine air data parameters from the received optical spectrum. The use of an optical filter array, particularly in the context of microlidar integrated photonics, enables air data systems with increased precision and nuance over traditional air data systems.

[0021] Referring to the figures, FIG. 1 shows an embodiment of an optical air data system 100 as described above. The air data system 100 is implemented on a substrate 102 made of silicon or a similar material. The substrate 102 can further include a chip, such as an integrated photonics chip. In some embodiments, the chip can be a microchip having a size of approximately 1 mm x 1 mm. The substrate 102 further includes an optical signal generator, such as a laser source 104, that can be configured to transmit a continuous wave signal at a frequency to a plurality of tunable optical filters 106. While three tunable optical filters 106 are shown in FIG. 1, the number of tunable optical filters can be expanded to any number required by the air data system 100. The system components described in FIG. 1 (and FIG. 2) can be coupled by free-space optics or by optical waveguides (e.g., fiber optic waveguides).

[0022] Each tunable optical filter 106 is configured to receive light from a laser source 104; however, whether the laser light passes through a designated optical filter 106 depends on how the tunable optical filter is tuned. When a tunable optical filter 106 is tuned to transmit only optical signals at the frequency of the laser source 104, then light from the laser source 104 can pass through the tunable optical filter 106 and subsequently be emitted into free space in a separate vector. Only one tunable optical filter 106 should be tuned to the resonant frequency of the laser source 104 at a given time. In this way, light from the laser source 104 passes through only one precisely tuned tunable optical filter 106 at a time. At a later time period, very close to the previous time period, another tunable optical filter is tuned to the frequency of the laser source 104, and the previous tunable optical filter is tuned to a different frequency such that light from the laser source 104 no longer passes through that tunable optical filter.

[0023] In some embodiments, and as described in further detail with respect to FIGS. 2-3 , the tunable optical filters are tuned so that in a default (inactive) state, each filter passes light at a frequency different from the frequency of the laser source 104. The tunable optical filters can then be activated by adjusting the frequency of the filter to match the frequency of the laser source 104. For example, each tunable optical filter can be coupled to a switch directed by a controller or microcontroller (not shown in FIG. 1 ) to control the tuning of each tunable optical filter. The controller can be configured to send a command signal to a designated tunable optical filter to set it to an inactive state, and can further be directed to set an activated tunable optical filter to its default (inactive) state.

[0024] Consistent with lidar-based principles, signals passing through the tunable optical filter 106 can be radiated in separate vectors in free space. When the signals impinge on objects in the environment (e.g., from Mie or Rayleigh scattering), the backscattered portions of the signals are reflected and received by the detector 108. The detector 108 can then transmit the backscattered portions to a processing system to determine various air data parameters from the acquired data, e.g., air velocity, temperature, and air density.

[0025] 2 shows an optical air data system 200 used to determine air data parameters. Air data system 200 functions similarly to air data system 100 with some differences that are described further herein. As with FIG. 1, air data system 200 can be implemented on a substrate 202, such as a silicon-based microchip.

[0026] In the air data system 200, the laser source 204 transmits an optical signal at a frequency to a set of tunable optical filters 206a, 206b, and 206c. One of the tunable optical filters 206a-206c is configured to pass a signal at the frequency of the laser source 204. In some embodiments, the tunable optical filters 206a-206c are coupled to a respective heater 207a-207c (e.g., a microheater). When the microheater is turned on, it heats the tunable optical filter, which then changes the frequency at which light can pass through the tunable optical filter. Thus, when activated, the tunable optical filter can pass the light beam transmitted by the laser source 204. As an example, assume that the tunable optical filter 206a is heated to match the frequency of the laser source 204. Light from the laser source 204 then passes through the tunable optical filter 206a to an emission grating coupler 208a, where the light can be emitted into free space. At a later time, tunable optical filter 206a is no longer heated, and therefore light from laser source 204 no longer passes through tunable optical filter 206a. Instead, tunable optical filter 206b is heated, in which case light propagates to tunable optical filter 206b, where it passes to radiation grating coupler 208b. Similarly, when tunable optical filters 206a and 206b are turned off, light can propagate through tunable optical filter 206c to radiation grating coupler 208c. Activation can be achieved via a controller or processor coupled to each heater.

[0027] The backscattered light is received from a grating coupler 210, which sends the backscattered signal to an optical filter array 220 to perform frequency decomposition. A reference signal may further be provided to the optical filter array 220 by a laser source 204. The optical filter array 220 includes a plurality of optical notch filters 212, each coupled to a respective detector 214. Each optical notch filter 212 is configured to pass a portion of the backscattered signal corresponding to a particular wavelength or frequency interval. In some embodiments, each optical notch filter 212 passes a different portion of the spectrum, allowing the spectrum of the backscattered signal to be decomposed into respective portions that are sent to respective detectors 214 for further processing.

[0028] For example, assume that the receive grating coupler 210 receives a backscattered signal having a frequency spectrum from 300 to 800 Hz. An optical notch filter 212 can be configured to pass a portion of the frequency spectrum from 300 to 320 Hz, while a second optical notch filter can be configured to pass a portion from 320 to 340 Hz. In this manner, the backscattered signal spectrum can be cascaded through different optical notch filters until each portion passes through an optical notch filter and onto a respective detector 214. More or fewer optical notch filters can be added to the optical filter array 220 to compensate for the overall frequency resolution of the received backscattered signal from the receive grating coupler 210. Additionally, while the frequency range of each optical notch filter 212 can be equally distributed (e.g., each optical notch filter 212 passes light in a 50 Hz range), the frequency ranges can also be modified so that the optical notch filters 212 have unequal frequency ranges.

[0029] The optical filter array 220 is coupled to the processing system 216 such that signals received by the plurality of detectors 214 are transmitted to the processing system 216. For example, each detector 214 can be configured to convert the optical signal received from its respective optical notch filter 212 into a corresponding electrical signal received by the processing system 216. The processing system 216 may include a processor 218, any one or combination of a microprocessor, digital signal processor, application-specific integrated circuit, field-programmable gate array, and / or other similar variations thereof. The processing system 216 may also include or function in conjunction with software programs, firmware, or other computer-readable instructions for performing various process tasks, calculations, and control functions used in the methods described below. These instructions are typically tangibly embodied on any storage medium (or computer-readable medium) used for storing computer-readable instructions or data structures.

[0030] Additionally, processing system 216 may include or be coupled to memory circuitry, such as memory 230. Memory 230 may include any available storage medium (or computer-readable medium) that can be accessed by a general-purpose or special-purpose computer or processor, or any programmable logic device. Suitable computer-readable media may include storage or memory media such as semiconductor, magnetic, and / or optical media, and may be embodied as storing instructions in a non-transitory computer-readable medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM, electrically erasable programmable ROM, flash memory, or other storage medium. Memory 230 may also include one or more databases for storing acquired data.

[0031] After processing system 216 receives the signal data from optical filter array 220, processing system 216 can then determine various air data parameters from the received data. In some embodiments, processing system 216 can transmit the air data parameters to other systems coupled to air data array 200, such as a flight management system. Processing system 216 can also transmit the air data parameters to a user interface, such as a cockpit display. Processing system 216 can optionally store the air data parameters in memory 230, where they can be accessed at a later time.

[0032] FIG. 3 shows a graph 300 of the voltage output of a set of three tunable optical filters per hour. For example, Filter 1 can correspond to tunable optical filter 206a, Filter 2 can correspond to tunable optical filter 206b, and Filter 3 can similarly correspond to tunable optical filter 206c. When Filter 1 is activated (e.g., heated), its voltage output increases to a high state as the signal from laser source 204 passes through it. As clearly shown in FIG. 3 , during this same time period, neither Filter 2 nor Filter 3 has a high voltage output when Filter 1 is activated. In a second period, Filter 1 is deactivated, and Filter 2 is activated such that the voltage output within Filter 2 reaches a high state. Finally, in a third period, Filter 3 is activated and reaches a high state while Filters 1 and 2 remain inactive. The process can be repeated as needed in the order described.

[0033] FIG. 4 shows a graph 400 of signal strength over time for emitted and received signals. The left peak 402 corresponds to the signal from the laser, while the right peak is the backscattered signal received from the emitted laser signal. Peak 404 is the frequency shift δf from the laser's resonant frequency to the backscattered resonant frequency due to Mie scattering with particles in the environment. Peak 406 corresponds to the frequency shift δf from the laser's resonant frequency as a result of Rayleigh scattering with particles in the environment. As shown in FIG. 4, various air data parameters can be determined from the distribution of frequencies received by the backscattered signal, such as pressure and temperature measurements.

[0034] 5A-5C show the structure and function of an exemplary optical notch filter 500 that can be implemented as the optical notch filter 212 used in the optical filter array 220. FIG. 5A shows a representation of the structure of the optical notch filter 500. FIG. 5B shows an enlarged view of a portion of the optical notch filter 500. Finally, FIG. 5C shows a graph illustrating the normalized power per wavelength of the output of the optical notch filter 500.

[0035] Referring to FIG. 5A, the optical notch filter 500 comprises a waveguide structure including a first waveguide 502 and a second waveguide 504. An input port 510 is positioned at a first end of the first waveguide 502, a reflection port 520 is positioned at a first end of the second waveguide 504 adjacent to the input port 510, and a drop port 530 is positioned at a second end opposite the first waveguide 502. A grating-assisted directional coupler 540 is positioned in a central portion of the waveguide structure between the input port 510 and the drop port 530. The grating-assisted directional coupler 540 has a periodic grating structure 542 on each of the first and second waveguides 502, 504, as shown in FIG. 5B.

[0036] Optical notch filter 500 is configured to receive light injected into input port 510, which directs the light into grating-assisted directional coupler 540. At the center of periodic grating structure 542 (FIG. 5B), a π phase shift in the phase of the modulation employed to form the grating structure generates a tightly confined optical field 550 at the resonant wavelength, with the light circulating around the π phase shift. The π phase shift is an abrupt change in the phase of the modulation that defines the grating. In other words, the π phase shift is an abrupt change in the spatial pattern of the waveguide modulation, such that the periodic structure of the waveguide modulation is shifted in spatial phase by π radians on either side of the interface.

[0037] As shown in Figure 5B, a π phase shift creates a tightly confined optical field at the resonant wavelength of the signal, allowing the signal to pass through to drop port 530. All other wavelengths exit through reflect port 520.

[0038] 5C, the peaks illustrated in the graph represent the portion of the signal that passes through the exemplary optical notch filter 500. The normalized power then decays exponentially as the frequency (and wavelength) of the signal spectrum increases or decreases from the resonant frequency.

[0039] Further details regarding exemplary optical notch filters that can be used in the embodiments disclosed herein are provided in US Pat. No. 10,788,340, the disclosure of which is incorporated by reference.

[0040] 6A is a cross-sectional side view of a grating coupler 600, such as a SiP grating coupler, that can be utilized as a grating coupler in the previously described air data system 200. Grating coupler 600 includes a periodic grating structure 610 formed as part of a waveguide layer 620 comprised of a higher refractive index material. Periodic grating structure 610 and waveguide layer 620 are embedded in a cladding layer 630 comprised of a lower refractive index material.

[0041] FIG. 6A illustrates the design parameters of a grating coupler 600 based on the following equation:

number

[0042] Thus, in some embodiments, grating coupler 600 can be incorporated on a chip to diffract in-plane light out of the plane from a waveguide or to receive out-of-plane light coupled into an in-plane waveguide.

[0043] FIG. 6B is a modeled graphical representation of the simulated performance of a grating coupler 600, such as a SiP grating coupler. FIG. 6B shows input light propagating along the grating, as well as a significantly weaker diffracted light field. The diffracted light field can be strong relative to the propagating field, reducing the required grating size by increasing the grating coefficient. This can then be done by increasing the etch depth of the grating.

[0044] 7 is a flowchart of a method 700 for determining air data parameters. Method 700 may be implemented via the techniques described with respect to FIGS. 1-6, but may also be performed via other techniques. The blocks of the flow diagram are arranged generally sequentially for ease of explanation. However, it should be understood that this organization is merely exemplary, and that the processing associated with the methods described herein (and the blocks illustrated in the figures) may occur in a different order (e.g., at least some of the processing associated with the blocks may be performed in a parallel and / or event-driven manner).

[0045] Method 700 begins at block 702 by generating an optical signal. The optical signal may be generated from a time-division multiplexed continuous wave laser. From block 702, method 700 proceeds to block 704 by sending at least a portion of the optical signal to one of a plurality of tunable optical filters based on the tuned frequency of the tunable optical filter. When the tunable optical filter is tuned to match the resonant frequency of the laser, the optical signal can pass through the tuned optical filter. However, when the tunable optical filter is not tuned (e.g., in an inactive default state), the optical signal is blocked from passing through the optical filter and instead propagates to the tuned optical filter. Therefore, only one optical filter should be tuned at a given time.

[0046] The method 700 then proceeds to block 706 by transmitting optical signal portions from each radiation grating coupler coupled to a respective tunable optical filter. The radiation grating couplers can be configured to transmit the optical signal portions into free space in particular directions. In an exemplary embodiment, the radiation grating couplers are positioned to transmit the optical signal portions in different directions from one another.

[0047] Proceeding next to block 708, the method 700 then receives a backscattered portion of the optical signal from the receiving grating coupler. In block 710, the method 700 filters the signal portion through an optical filter array based on the frequency (or wavelength) resolution of the backscattered portion. As described above, the optical filter array includes multiple optical notch filters, each coupled to a detector. The optical filter array can perform frequency resolution of the received backscattered portion by configuring each optical notch filter in the array with a distinct frequency (or wavelength) range. Frequencies or wavelengths of the backscattered portion that fall within the range can pass through the optical notch filter, while not being cascaded through the optical filter array until they are propagated to the appropriate optical notch filter.

[0048] The method 700 then proceeds to block 712 by detecting a signal corresponding to the filtered signal portion from each detector in the optical filter array. The filtered signal can then be transmitted to a processing system coupled to the optical filter array.

[0049] The method 700 then proceeds to block 714 by determining air data parameters based on the detected signals. Such air data parameters may include air velocity, temperature, pressure, and air density.

[0050] The methods and techniques described herein may be implemented in digital electronic circuitry, or in programmable processors (e.g., special-purpose processors or general-purpose processors such as computers), firmware, software, or various combinations of each. Apparatuses embodying these techniques may include appropriate input and output devices, a programmable processor, and a storage medium tangibly embodying program instructions for execution by the programmable processor. Processes embodying these techniques may be performed by a programmable processor executing a program of instructions to perform a desired function by operating on input data and generating appropriate output. The techniques may advantageously be implemented in one or more programs executable on a programmable system including at least one programmable processor coupled to receive data and instructions and transmit the data and instructions to a data storage system, at least one input device, and at least one output device.

[0051] Generally, a processor receives instructions and data from a read-only memory and / or a random-access memory. Suitable storage devices for tangibly embodying computer program instructions and data include, for example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and DVD disks. Any of the above may be supplemented by, or incorporated in, specially designed ASICs.

[0052] The terms "approximately" or "substantially" mean that, from the perspective of one skilled in the art, a specified value or parameter may be slightly modified unless such modification results in a non-compliance of the process or structure with the illustrated embodiment. Finally, the term "exemplary" does not imply ideal, essential, or preferred features of the invention, but merely indicates that the accompanying description is used as an example. Illustrative Embodiments

[0053] Example 1 includes a photonics substrate; a laser source operatively coupled to the photonics substrate, the laser source operable to emit a light beam; a plurality of tunable optical filters on the photonics substrate, the tunable optical filters in optical communication with each other and with the laser source; a plurality of emission grating couplers on the photonics substrate, each emission grating coupler respectively coupled to an output of one of the tunable optical filters, each emission grating coupler configured to emit a light beam received from the output of a respective tunable optical filter into a target region in a different direction; at least one reception grating coupler on the photonics substrate, the at least one reception grating coupler configured to receive scattered light from the target region; and a passive optical filter array on the photonics substrate in optical communication with the reception grating coupler. and a passive optical filter array configured to receive scattered light from the receiving grating couplers, the passive optical filter array comprising a plurality of optical notch filters operative for frequency selection and a plurality of optical detectors each respectively coupled to an output of one of the optical notch filters, each of the optical notch filters configured to pass scattered light received in a corresponding wavelength range to a respective one of the optical detectors, each corresponding wavelength range being distinct, the passive optical filter array operative to perform frequency spectral decomposition of the received scattered light into a plurality of signals, and the integrated photonics chip including one or more tunable optical filters operative to enable transmission of the light beam emitted from the laser source to one of the emission grating couplers at any given time, such that the light beam is emitted into the target region from each of the emission grating couplers at different times.

[0054] Example 2 includes the integrated photonics chip of example 1, further comprising a plurality of micro-heaters coupled to the plurality of tunable optical filters, the plurality of micro-heaters configured to heat the plurality of tunable optical filters such that a resonant frequency of each tunable optical filter matches a resonant frequency of the laser source.

[0055] Example 3 includes the integrated photonics chip of example 2, further comprising a controller coupled to the plurality of micro-heaters, the controller configured to selectively activate or deactivate each micro-heater such that only one micro-heater is activated at any given time.

[0056] Example 4 includes the integrated photonics chip of any of Examples 1-3, further comprising a processing system coupled to the passive optical filter array, the processing system comprising one or more processors configured to receive the plurality of signals, and to determine at least one air data parameter based on the received plurality of signals.

[0057] Example 5 includes the integrated photonics chip of example 4, wherein the at least one air data parameter includes at least one of air velocity, pressure, temperature, and air density.

[0058] Example 6 includes the integrated photonics chip of any of Examples 1-5, wherein the laser source is configured to generate a time-division multiplexed continuous wave signal.

[0059] Example 7 includes the integrated photonics chip of any of Examples 1-6, wherein the laser source is configured to transmit a reference signal to the passive optical filter array.

[0060] Example 8 includes the integrated photonics chip of any of Examples 1 to 7, wherein each of the plurality of optical notch filters comprises a waveguide structure including a first waveguide and a second waveguide, the waveguide structure comprising: an input port located at a first end of the first waveguide; a reflection port located at a first end of the second waveguide and adjacent to the input port; a drop port located at a second end opposite the first waveguide; and a grating-assisted directional coupler located in a central portion of the waveguide structure between the input port and the drop port, the grating-assisted directional coupler comprising a periodic grating structure on each of the first waveguide and the second waveguide.

[0061] Example 9 includes the integrated photonics chip of example 8, wherein the first waveguide is configured to receive light injected into the input port and direct the light to the grating-assisted directional coupler, wherein the periodic grating structure of the grating-assisted directional coupler is configured to produce a π phase shift, wherein the periodic structure of the waveguide modulation is shifted in spatial phase by π radians on either side of an interface, an abrupt change in the spatial pattern of the waveguide modulation creating a confined field of light at a resonant wavelength with the light circulating around the π phase shift, wherein a selected wavelength of light is transmitted to the drop port and all other wavelengths of light exit through the reflect port.

[0062] Example 10 relates to an illumination system comprising: a laser source operative to emit a light beam; a plurality of tunable optical filters in optical communication with each other and with the laser source; a plurality of emission grating couplers each respectively coupled to an output of one of the tunable optical filters, wherein each emission grating coupler is configured to emit a light beam received from the output of a respective tunable optical filter into a region of interest in a different direction; and a controller coupled to the plurality of tunable optical filters, the controller configured to activate the tunable optical filters such that an activated tunable optical filter operates to enable transmission of the light beam to a corresponding emission grating coupler during a given period of time; and an air data detection system in operative communication with the illumination system, the air data detection system including at least one receiving grating coupler configured to receive scattered light from the region of interest; the passive optical filter array is in optical communication with the coupler and configured to receive scattered light from the receiving grating coupler, the passive optical filter array comprising a plurality of optical notch filters operative for frequency selection and a plurality of optical detectors, each optical notch filter configured to pass scattered light received in a corresponding frequency range to a corresponding one of the optical detectors, each corresponding frequency range being distinct, the passive optical filter array operative to perform frequency spectral decomposition of the received scattered light into a plurality of signals; and a processing system operatively coupled to the air data detection system, the processing system configured to receive the plurality of signals, the processing system operative to determine at least one air data parameter based on the received plurality of signals.

[0063] Example 11 includes the optical air data system described in Example 10, where the light emission system and the air data detection system are on a silicon microchip.

[0064] Example 12 includes the optical air data system of any of Examples 10-11, wherein the light emitting system further comprises a plurality of microheaters coupled to the plurality of tunable optical filters, the plurality of microheaters configured to heat the plurality of tunable optical filters such that a resonant frequency of each tunable optical filter matches a resonant frequency of the laser source.

[0065] Example 13 includes the optical air data system of example 12, wherein the controller is coupled to the plurality of microheaters and configured to selectively activate or deactivate each tunable optical filter such that the light beams are emitted from each of the emission grating couplers into the target region at different times.

[0066] Example 14 includes the optical air data system of any of Examples 10 to 13, wherein the processing system includes one or more processors configured to determine two or more air data parameters based on the received plurality of signals.

[0067] Example 15 includes the optical air data system of example 14, wherein the two or more air data parameters include air velocity, pressure, temperature, or air density.

[0068] Example 16 includes the optical air data system of any of Examples 10-15, wherein the laser source is configured to generate a time division multiplexed continuous wave signal.

[0069] Example 17 includes the optical air data system of any of examples 10-16, wherein the laser source is configured to transmit the reference signal to the air data detection system.

[0070] Example 18 includes the optical air data system of any of examples 10-17, wherein the light emitting system comprises a light detection and ranging (lidar) system.

[0071] Example 19 includes the optical air data system of any of Examples 10 to 18, wherein each of the plurality of optical notch filters comprises a waveguide structure including a first waveguide and a second waveguide, the waveguide structure comprising: an input port positioned at a first end of the first waveguide; a reflection port positioned at a first end of the second waveguide and adjacent to the input port; a drop port positioned at a second end opposite the first waveguide; and a grating-assisted directional coupler positioned in a central portion of the waveguide structure between the input port and the drop port, the grating-assisted directional coupler including a periodic grating structure on each of the first waveguide and the second waveguide.

[0072] Example 20 includes a method including generating an optical signal; sending the optical signal to a plurality of tunable optical filters, wherein the optical signal is sent to each of the plurality of tunable optical filters at different time periods; transmitting the optical signal from each of the plurality of tunable optical filters to a target area such that the optical signal is emitted into the target area at different times; receiving a backscattered signal based on the transmitted optical signal; filtering the backscattered signal into a plurality of filtered signal portions based on a frequency or wavelength resolution of the backscattered signal; detecting the plurality of filtered signal portions; and determining at least one air data parameter based on the detected filtered signal portions.

[0073] Although specific embodiments have been illustrated and described herein, those skilled in the art will recognize that any configuration which is expected to achieve the same purpose may be substituted for the specific embodiments shown. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.

Claims

1. 1. An integrated photonics chip, comprising: a photonics substrate; a laser source operably coupled to the photonics substrate, the laser source operative to emit a beam of light; a plurality of tunable optical filters on the photonics substrate, the tunable optical filters being in optical communication with each other and with the laser source; a plurality of radiation grating couplers on the photonics substrate, each radiation grating coupler coupled to an output of one of the tunable optical filters, each radiation grating coupler configured to emit the light beam received from the output of its respective tunable optical filter into a target area in a different direction; at least one receiver grating coupler on the photonics substrate configured to receive scattered light from the region of interest; a passive optical filter array on the photonics substrate in optical communication with the receiving grating coupler, the passive optical filter array configured to receive the scattered light from the receiving grating coupler, the passive optical filter array comprising a plurality of optical notch filters operative for frequency selection, and a plurality of optical detectors, each optical notch filter configured to pass the received scattered light in a corresponding wavelength range to a respective one of the optical detectors, each corresponding wavelength range being distinct, the passive optical filter array operative to perform a frequency spectral decomposition of the received scattered light into a plurality of signals; an integrated photonics chip, wherein the light beam emitted from the laser source is routed to one or more of the tunable optical filters, which operate to enable transmission of the light beam to one of the emission grating couplers at any given time, such that the light beam is emitted into the target region at different times from each of the emission grating couplers.

2. 10. The integrated photonics chip of claim 1, further comprising a plurality of micro-heaters coupled to the plurality of tunable optical filters, the plurality of micro-heaters configured to heat the plurality of tunable optical filters such that a resonant frequency of each tunable optical filter matches a resonant frequency of the laser source.

3. 3. The integrated photonics chip of claim 2, further comprising: a controller coupled to the plurality of micro-heaters, the controller configured to selectively activate or deactivate each micro-heater such that only one micro-heater is activated at any given time.

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