N242-104 TITLE: Fast 1-to-N Polarization Maintaining Fiber Optical Switches for the Near Infrared (NIR)

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Microelectronics; Quantum Science; Space Technology

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: Develop a technology that allows for near-infrared (NIR) light in a fiber waveguide to be rapidly and efficiently directed along one of many fiber waveguides in nanosecond scale time periods.

DESCRIPTION: Atomic accelerometers are important elements of advanced inertial navigation and timing systems. In recent years, there has been significant effort to reduce the size, weight, and power (SWaP) of various subsystems. One challenge of miniaturizing these sensors is precisely delivering the pulse sequence emanating from a single optical source to the multiple optical axes of a sensor.

Appropriate pulse shapes require nanosecond switching speeds, and avoiding unwanted atomic transitions requires high extinction ratios. These are currently achievable in bulk acousto-optic crystals. Currently, fiber switches can be found based on mechanical, Micro-Electromechanical Systems (MEMS), and solid-state approaches [Refs 1, 2]; however, none meet all requirements simultaneously.

The objective of this SBIR topic is to develop a compact NIR 1-N port fiber optic switch suitable for pulse shaping and switchyard roles in an atomic interferometer. This will replace the bulk acousto-optics or multiple laser sources currently used to achieve the same result, resulting in drastically reduced size and complexity. To meet the pulse shape role the switch must have rise and fall times on the order of nanoseconds and be capable of MHz repetition rates. To meet the switchyard role it must have high reliability, low insertion loss, ultra-low crosstalk, and at least four ports.

Technical requirements for 1-N port switch are:

• Operating wavelength: 780 nm [threshold], devices compatible (not necessarily tunable) with 400-900 nm [objective]

• Fiber type: Polarization maintaining

• Crosstalk / extinction ratio: > 20 dB [threshold], > 30 dB [objective]

• Rise and fall time: < 50 ns [threshold], < 20 ns [objective]

• Insertion loss: < 6 dB [threshold], < 3 dB [objective]

• Switching time: < 1 µs [threshold], < 0.1 µs [objective]

• Number of ports: 4 [threshold], 6 [objective]

• Optical power handling (at device input): > 100 mW [threshold], > 500 mW [objective]

• Electrical power draw: < 1 W [threshold], < 100 mW [objective]

PHASE I: Perform a design and materials study to assess the feasibility of the selected technology and its ability to meet the goals above. The final report will include

• A discussion of how the technological approach will satisfy the requirements of the ultra-fast NIR optical switch.

• An evaluation of the technology’s SWaP for the component that would be built in Phase II.

• A discussion of the fabrication process including an assessment of risks and risk mitigation strategies.

• A discussion of whether the proposed technology is compatible with integration onto a photonic integrated circuit (this is not a requirement).

The Phase I Option, if exercised, will include the initial design specifications and description to build a prototype solution in Phase II.

PHASE II: Fabricate, test, and deliver three (3) prototypes of the design developed in Phase I. The completed prototypes shall be tested against the performance goals listed above. The final report shall include an assessment of potential near-term and long-term development efforts that would improve the technology’s technical performance, SWaP, and ease of fabrication. It shall also include an evaluation of the cost of fabrication and how that might be reduced in the future. The prototypes shall be delivered by the end of Phase II.

PHASE III DUAL USE APPLICATIONS: Based on the prototypes developed in Phase II, continue development towards a production run of the 1-N port fiber switch.

In addition to advancing a quantum sensing capability for military/strategic applications, this technology has applications in the telecom industry, Light Detection and Ranging (LIDAR) systems, and future quantum network infrastructure.

REFERENCES:

1. Templier, S., et al. "Carrier-suppressed multiple-single-sideband laser source for atom cooling and interferometry." Physical Review Applied 16.4 (2021): 044018. https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.16.044018
2. K. F. Lee and G. S. Kanter. "Low-Loss High-Speed C-Band Fiber-Optic Switch Suitable for Quantum Signals." IEEE Photonics Technology Letters, vol. 31, no. 9, 1 May 2019, pp. 705-708,. doi: 10.1109/LPT.2019.2905593. https://ieeexplore.ieee.org/abstract/document/8668492

KEYWORDS: fiber optic, switch; near infrared; NIR; inertial sensors; atomic clocks; atomic accelerometers

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