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Mid-Wave Infrared Fiber Amplifier



OBJECTIVE: Develop and demonstrate a high-power mid-wave infrared (MWIR) fiber amplifier for quantum cascade lasers (QCLs) capable of output power scaling up to 1 kilowatt (kW). 

DESCRIPTION: High power mid-wave infrared (MWIR) laser sources in the wavelength range of 4.6 to 5 micrometers are of great interest in defense applications. A major limitation to developing these sources is the lack of materials that lase directly in the MWIR. Materials that do lase directly in the MWIR are either inefficient, require cryogenic cooling, or have other challenges. Correspondingly, most high-power laser systems in this wavelength region rely on the use of nonlinear conversion processes, resulting in low efficiencies and high size, weight, and power (SWaP). Recently, QCLs [Ref 1] have emerged as a viable direct source, offering MWIR lasers for naval infrared countermeasure (IRCM) applications with increased performance. However, relatively low electrical-to-optical efficiencies of these QCL devices have resulted in approximately over 75-80% of the electrical energy input to the QCL dissipated as heat. Future-generation IRCM systems and missile defense may benefit from the use of MWIR IRCM lasers with kW capability. None of today’s commercially available QCLs and beam combining schemes are capable of delivering up to and beyond kW output power levels with diffraction limited beam quality. It is therefore the goal of this SBIR topic to further the development of MWIR rare earth-doped fiber amplifiers [Ref 2] for QCLs that potentially will reach kW level in continuous wave regime with excellent beam quality (M2 <1.5) and high slope efficiency. The successful demonstration of a MWIR fiber laser amplifier for QCL devices would serve to advance any application requiring higher power QCL performance. Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. Owned and Operated with no Foreign Influence as defined by DOD 5220.22-M, National Industrial Security Program Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Security Service (DSS). The selected contractor and/or subcontractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances, in order to perform on advanced phases of this contract as set forth by DSS and NAVAIR in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material IAW DoD 5220.22-M during the advance phases of this contract. 

PHASE I: Design and analyze a best-performance MWIR fiber amplifier architecture in the wavelength range of 4.6 to 5 micrometers. Demonstrate fiber-based amplification of a QCL based on the best available rare earth-doped chalcogenide fiber and laser diodes or fiber lasers to pump the amplifier in a bench top experiment. Provide the first-light fiber amplification power-scaling results and show path to meeting Phase II goals. The Phase I effort will include prototype plans to be developed under Phase II. 

PHASE II: Optimize the rare earth-doped chalcogenide fiber design and transition the Phase I laser to an all-glass, monolithic fiber amplifier architecture that is capable of producing up to 1 kW output power. Completely characterize the fiber amplifier architecture, in terms of gain at 4.5 micron, slope efficiency (percentage of the signal power with respect to pump power), and gain bandwidth. Demonstrate the developed prototype. It is probable that the work under this effort will be classified under Phase II (see Description section for details). 

PHASE III: Fully develop and transition the high power MWIR fiber amplifier for DoD applications in the areas of Directed Infrared Countermeasures (DIRCM), advanced chemicals sensors and laser detection and ranging (LIDARs). The DoD has a need for advanced, high-power MWIR laser sources of which the output power can readily be scaled for current- and future-generation DIRCMs, LIDARs, and chemicals/explosives sensing. The commercial sector can also benefit from the crucial, game-changing technology development in detection of toxic gases, environmental monitoring, and non-invasive health monitoring and sensing. 


1. Bai, Y., Bandyopadhyay, N., Tsao, S., Slivken, S. and Razeghi, M. “Room Temperature Quantum Cascade Lasers with 27% Wall Plug Efficiency.” Applied Physics Letters, 2011.

KEYWORDS: Quantum Cascade Laser; QCL; Thermal Load; Scaling; Mid-Wave Infrared; MWIR; Brightness; Fiber Amplifier 

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