N161-005 TITLE: Compact Ultraviolet (UV) Laser Emitter in the 320-355 Nanometer (nm) Spectral Range

TECHNOLOGY AREA(S): Air Platform, Chemical/Biological Defense, Electronics

ACQUISITION PROGRAM: PMA 272 Advanced Tactical Aircraft

OBJECTIVE: Develop a compact, robust and efficient high-power ultraviolet (UV) laser emitter operating at room temperature in the wavelength range between 320-355 nanometer (nm).

DESCRIPTION: High-power, compact and reliable UV laser emitters in the wavelength range between 320-350 nm are very critical for various naval applications such as countermeasure for aircraft protection, advanced chemicals sensors based on Raman spectroscopy and laser identification detection and ranging (LIDAR).

There are at present commercially available UV laser technologies such as gas and solid-state lasers with frequency conversion that can emit in the wavelength range under 350 nm and produce high powers with narrow linewidths. These technologies, however, are generally too heavy, bulky, inefficient and inadequately ruggedized to meet the Navy�s stringent size, weight and power (SWaP) and reliability requirements [1].

There are a couple of potential emerging technologies that could meet Navy SWaP specifications. One of the technologies under consideration for this program is based on the recent advances in technologies of Gallium Nitride (GaN) and related materials that have attained successful realization and commercialization of blue and green light emitting diodes (LEDs) and white lighting devices, and blue laser diodes for optical storage. However, the performance of these laser diodes based on high bandgap AlGaN materials are rendered inefficient primarily due to the inadequate material quality of Aluminum Gallium Nitride (AlGaN), lack of readily available lattice matched substrates resulting in formation of high threading dislocations in the grown layers, poor ohmic contacts and current crowding due to low carrier concentration and mobility, and poor thermal conductivity of the composite of epitaxy materials and substrate [2]. There have been recent advances in epitaxial growth that has alleviated markedly the germination and propagation of dislocations and the improved growth technique combined with novel laser design has a promising potential to mitigate many of the aforementioned issues. Moreover, semiconductor based solutions are readily power-scalable to mitigate the challenge of low emission power from a single emitter via either coherent or spectral beam combining of multiple emitters with single output aperture and excellent beam quality [3].

Another alternative and more mature technology is based on frequency conversion of high-power solid state laser via nonlinear optical process. Since a typical system usually consists of multiple stages of active and passive optical elements, such a system is inherently inefficient and bulky in terms of size and weight. Innovative system designs are therefore needed to minimize the size and weight and maximize the efficiency in order to meet the current laser emitter�s SWaP requirements.

The objective of this program is to develop compact, efficient, high-power UV lasers with continuous wave (CW) or average output power >1 watt (W) if operating in pulsed mode at periodic repetition frequency no less than 1kHz, wall-plug efficiency >10% and beam quality with M2 < 2 in the spectral range between 320 - 355 nm. The size of the laser head is required to be no more than 3 cubic inch. Both of the above-mentioned approaches will be considered if the proposers can propose convincing viable technologies that can meet the performance and size specifications.

PHASE I: Demonstrate the feasibility of a design for a UV laser emitter in the spectral range between 320 - 355 nm that can produce continuous wave (CW) or average output power >1 W if operating in pulsed mode at periodic repetition frequency no less than 1kHz, wall-plug efficiency >10%, M2 < 2 and size no bigger than 3 cubic inches. A viable design path forward for further increasing the output power beyond 1W at room temperature scheme should be proposed and included as part of the deliverable for Phase I.

PHASE II: Develop a prototype of compact UV laser emitter based on the proposed design in Phase I that meets the specifications stated in Phase I. Also demonstrate a viable path forward to power-scale the proposed baseline design in Phase II to beyond 5 W while maintaining beam quality with M2< 2. It is critical to incorporate manufacturing cost reduction as part of the design criteria throughout all the design phases in all phases of this program.

PHASE III DUAL USE APPLICATIONS: Produce three compact UV lasers based on the Phase II final design and perform qualification tests to validate the design and performance on designated avionic platforms in a relevant military environment. A compact, efficient, and high-power UV laser will enable a wide range of commercial applications including: remote detection of biological and chemical compounds; compact atomic clocks for precise timing and navigation; high precision materials processing and real-time medical diagnostics. For example, in Raman spectroscopy specific compounds can be identified with higher precision when exposed to a UV laser compared to an infrared laser because the scattering cross-section is over 100 times larger at UV wavelengths, increasing the Raman signal.

REFERENCES:

1. MIL-STD-810G � Department of Defense Test Method Standard: Environmental Engineering Considerations Laboratory Tests (31 Oct 2008). Retrieved from http://everyspec.com/MIL-STD/MIl-STD-0800-0899/MIl-STD-810G_12306/

2. Bayram, C., Pau, J.L., McClintock, R., & Razeghi, M. (2008)., Applied Physics B: Lasers and Optics, Vol. 95, p. 307-314.

3. Fan, T.Y. (2005). Laser beam combining for high-power, high-radiance sources, IEEE Journal of Quantum Electronics, 11, 563. Retrieved from http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1516122

KEYWORDS: Lidar; Beam Combining; AlGaN; UV lasers; frequency conversion; GaN

TPOC-1: 760-939-0239

TPOC-2: 301-757-7970

Questions may also be submitted through DoD SBIR/STTR SITIS website.

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between December 11, 2015 and January 10, 2016 you may talk directly with the Topic Authors (TPOC) to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting January 11, 2016 , when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (16.1 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 16.1 topic under which they are proposing.

If you have general questions about DoD SBIR program, please contact the DoD SBIR Help Desk at 800-348-0787 or [email protected]