N232-105 TITLE: Liquid Crystal on Silicon (LCoS) Micro-Displays for Deep Learning Acceleration

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Microelectronics;Trusted AI and Autonomy

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Research, develop, and fabricate micro-scale, high-resolution, high-refresh rate liquid-crystal-on-silicon (LCoS) micro-displays.

DESCRIPTION: The Office of Naval Research (ONR) is currently developing a range of electro-optical compute accelerators (EOCAs) for small-scale, low-power, lensless computer-vision applications. To create the next-generation versions of EOCAs, we are seeking proposals aimed at the fabrication of custom liquid-crystal micro-displays. We are interested in micro-scale, high-resolution liquid-crystal displays, similar to what would be found in commercial virtual-reality headsets.

The micro-displays we need have several requirements not found in existing commercial offerings. Some additional research is hence needed. The micro-displays must be small (20 millimeter diagonal length or less) and high resolution (2048x1080 pixels or higher). The micro-displays should be grayscale-only and capable of supporting and implementing 8-bit grayscale values with the option to potentially support 16-bit values. A low response time (about 3 milliseconds or lower), and hence high frame rate (240 frames per second or higher), is needed to perform sensing and processing tasks at a level needed for realizing certain autonomy capabilities. The micro-displays should also come in back-lit and non-back-lit, transparent variations. In the latter case, the display should be made as transparent as possible so that light can travel through the liquid-crystal layer and be predominantly attenuated by the point-spread functions that will be shown on them. The EOCAs will have active-pixel sensors placed almost immediately behind the transparent liquid-crystal layer of the micro-displays, so no occluding materials can be present; any electronics should be located at the periphery of the displays and incorporated into the baffling. Both the back-lit and non-back-lit, transparent displays should interface with printed-circuit driver boards that will be developed and fabricated by the awardee as part of this SBIR topic.

Design Requirements:

- Size: < = 20 millimeter diagonal length

- Resolution: > = 2048x1080 pixels

- Display Color: Monochromatic

- Refresh Rate: > = 240 frames per second

- Pixel Bit Depth: > = 8 Bits

- Cell Gap Uniformity: < = 5%

- Back-lit Display Brightness: > = 1000 candela per square meter

- Interface(s): Multi-lane Mobile Industry Processor Interface (MIPI DSI) with High-Definition Multimedia Interface (HDMI) 2.1, or better, to provide inputs to the printed-circuit driver board

Technical challenges: Ideally, the displays should be as low power as possible. An integrated driver will likely be necessary to achieve power draws of under 400 milliwatts while the display is active. The displays may be used for applications in harsh environments not currently considered by the acquisition program. A path forward for high-temperature operating conditions (greater than 70 degrees Celsius) should be established in the design stage, even if it is not implemented in the prototypes.

Supporting incredibly high frame rates will not be feasible with present HDMI standards. Pre-buffering many image frames may not always be an option. The displays will hence, practically, be limited to the rates and resolution supported by the current HMDI 2.1/2.1a standard, which will be approximately 240 frames per second, during evaluation by the Navy. The designed displays will eventually be merged with a custom application-specific integrated circuit (ASIC) chip to drive them at the highest frame rate offered by a multi-lane MIPI connection.

PHASE I: Produce a LCoS design that satisfies the above criteria. If the design cannot meet the design objectives an analysis or discussion of the potential should be included in the Phase I report. Modeling, simulation, or comparison to similar developments should be used to justify design decisions.

PHASE II: Fabricate two to three prototype systems for evaluation. The prototype demonstration should achieve or show potential for meeting the design requirements. Perform detailed analysis on ruggedness and compatibility with Navy unmanned underwater vehicle handling, storage, and environmental operating conditions. Testing will be conducted by both the performer and by Navy personnel. Cost effectiveness and manufacturability feasibility should be addressed as part of the prototype test and evaluation. The appropriate acquisition program office will be consulted for any additional evaluation metrics needed for Phase III.

PHASE III DUAL USE APPLICATIONS: Build an advanced LCoS prototype that meets appropriate technology readiness level (TRL) metrics set by the acquisition program office. Support the Navy for test and validation of the system for certified Navy use. Explore the potential to transfer the LCoS technology for commercial use. Commercial applications might include visual detection and tracking systems, low-power processing for commercial UxV systems, and large-scale supercomputing resources. Develop manufacturing plans to facilitate transition to a UUV program of record.

REFERENCES:

1. Yang, J.P.; Wu, J.P.; Wang, P.S. and Chen, H.M.P. "Characterization of the spatially anamorphic phenomenon and temporal fluctuations in high-speed, ultra-high pixels-per-inch liquid crystal on silicon phase modulator." Optics Express, 27(22), 2019, pp. 32168-32183. DOI: 10.1364/OE.27.032168
2. Pivnenko, M.; Li, K. and Chu, D. "Sub-millisecond switching of multi-level liquid crystal on silicon spatial light modulators for increased information bandwidth," Optics Express, 29(16), 2021, pp. 24614-24628. DOI: 10.1364/OE.429992
3. Yang, H. and Chu, D.P. "Phase flicker in liquid crystal on silicon devices." Journal of Physics: Photonics, vol. 2(3): 032001, 2020, pp. 1-19. DOI: 10.1088/2515-7647/ab8a57

KEYWORDS: Liquid-Crystal Display, Optical Processing, Machine Learning, Computer Vision, Deep Network, Frame Rate

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