The Department of Defense, specifically the United States Air Force (USAF), is seeking proposals for the development of two-micron wavelength fiber-coupled semiconductor lasers under the SBIR program. The objective is to create and deliver five packaged units of compact laser sources that emit over 500 mW of continuous wave (CW) power, with specific requirements for beam quality, weight, and volume. These lasers are intended for use in compact LADAR systems, which are critical for various intelligence, surveillance, and reconnaissance (ISR) applications. Interested parties must submit their proposals by November 6, 2024, and can find more information on the solicitation through the provided link to the DOD SBIR/STTR website.

## Description

Compact LADAR systems are desirable for a variety of USAF and USSF intelligence, surveillance, and reconnaissance (ISR) applications. Specifically a compact CW source emitting between a wavelengths of 2000-2100 nm at room temperature is required. Promising breakthroughs in semiconductor laser design utilize photonic crystal surface emitting lasers (PCSELs) to output high powers and beam quality. PCSELs support single mode lasing over millimeter scales and emit a narrow divergence beam allowing for efficient coupling into a fiber enabling use to seed photonic integrated circuits (PICs) and fiber amplifiers.GaAs PCSELs have achieved 50 W of CW single mode power at room temperature emitting at 950 nm with divergence 0.05&deg; and a 3 pm FWHM from a 3 mm aperture device [1]. However to operate at the wavelengths beyond 2000 nm, another material must be used such as GaSb or InP. GaSb based edge emitting lasers (EEL) have demonstrated 850 mW of multimode CW output at room temperature [2], but better beam quality is required to couple 500 mW into a single mode fiber. A surface-emitting laser is an attractive option as the power grows with the square of the aperture size. GaSb vertical cavity surface emitting lasers (VCSELs) have reached 0.8 mW of CW power in a single mode [3], but the scalability is limited while maintaining single mode operation. GaSb PCSELs have reached tens of mW of CW output power at a wavelength of 2 &mu;m with a 200 &mu;m aperture emitting with multimode output [4]. More power should be feasible by scaling the device size and potentially using MOCVD as done in GaAs [1] opposed to MBE in recent GaSb work [4].The requirements for this call are the development and delivery of five packaged units of compact laser sources with 500 mW of CW power out of polarization-maintaining single mode fiber. Beam quality should be M2 &lt; 1.2 for efficient coupling. The lasing wavelength must be between 2000 nm and 2100 nm. The total weight of each unit must be &lt;1 kg and volume &lt;1000 cm3. Engineering a variation of bandwidths between the five units such as 0.05 nm, 0.1 nm, 0.2 nm, 0.5 nm, and 1 nm is desirable. The target intrinsic linewidth is &lt;1 kHz.Preference will be given to designs that offer higher output power, higher wall-plug efficiency, degree of polarization, room temperature operation, and narrow linewidth without the use of external cavity elements. No government materials, equipment, data, or facilities will be provided.INVESTMENT END STATE: A successful result will be the development of processes necessary and delivery of five individually packaged low-SWaP semiconductor lasers with &gt;500 mW of CW coupled into a single mode polarization maintaining fiber.

## Objective

Develop and package surface-emitting semiconductor lasers as low-size weight and power (SWaP) sources emitting at two microns with &gt;500 mW of continuous wave (CW) power coupled to polarization maintaining fiber.

## Phase I

As this is a Direct-to-Phase-II (D2P2) topic, no Phase I awards will be made as a result of this topic. To qualify for this D2P2 topic, the Air Force expects the applicant(s) to demonstrate feasibility by means of a prior &ldquo;Phase I-type&rdquo; effort that does not constitute work undertaken as part of a prior or ongoing SBIR/STTR funding agreement. Applicants interested in participating in this topic must include in their response to this topic Phase I feasibility documentation that substantiates the scientific and technical merit and &quot;Phase I-type&quot; effort such as a developed concept for a workable prototype, results for comparable devices in other wavelength bands, or design to address, at a minimum, the requirements for 2000-2100 nm semiconductor lasers. Documentation should include all relevant information including, but not limited to, technical reports, test data, prototype designs/models, and performance goals/results for establishing the scientific and economic feasibility of the proposed work. Work submitted within the feasibility documentation must have been substantially performed by the offeror and/or the principal investigator (PI).

## Phase II

Demonstrate a surface emitting laser at a wavelength between 2000-2100 nm and fiber couple &gt;500 mW of CW single mode power. The proposal should provide demonstrations for multiple use cases. These are to include: (1) Maximum CW power operation with power stability measurements with periodic wavelength and beam profile characterization, (2) maximum quasi-CW power operation with power stability measurements and periodic wavelength and beam profile characterization, and (3) pulse characterization for microsecond and sub-microsecond (100-200 ns) at various drive currents.

## Phase III: Dual Use Applications

Scaled manufacturing in a relevant commercial fabrication/foundry environment with packaging sufficient for integration in larger systems. Refine processes to increase device yield. Work towards reaching upper limits of millimeter scale devices including current and thermal management.

Two micron wavelength fiber-coupled semiconductor lasers

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