TECHNOLOGY AREA(S): Electronics
OBJECTIVE: To develop high power, high efficiency diode emitters while maintaining single mode emission.
DESCRIPTION: Poor efficiency in high energy lasers (HELs) is a key driver to the large Size, Weight, and Power (SWaP) requirements of HEL Weapon Systems. Current HEL Weapon Systems are primarily using spectrally beam combined or coherently beam combined fiber laser technology. Electrical to optical efficiency of these HELs are at best 40% after diode pump power into the fiber and fiber gain media losses. One potential approach to improving the efficiency is to remove the fiber laser gain media and directly beam combine single mode diode lasers. For this approach to be practical the power level, beam quality, and efficiency of single mode emitters must be sufficient. Individual diode lasers have shown up to efficiencies greater than 75% and power levels on the order of kilowatts, but most often beam quality suffers when these parameters are achieved. This solicitation is looking for a solution to achieve all parameters in one prototype.
• Power (single emitter): Threshold: 4W; Objective: >10W
• Electrical to Optical Efficiency: Threshold: 50%; Objective: 70%
• Beam Quality (M2): Threshold: 1.75; Objective: 1.1
• Wavelength: Wavelengths that transmit through the atmosphere
PHASE I: The phase I effort shall include analysis and design of the proposed diode emitter concept. The analysis shall provide confidence that the proposed concept design will be successful in meeting the specifications. Power, efficiency, and beam quality expectations out of a single emitter shall be addressed in the Phase I effort.
PHASE II: During phase II, the phase I designs will be utilized to fabricate, test and evaluate a single emitter. The power, efficiency, and beam quality specifications shall be demonstrated during the phase II effort.
PHASE III: During phase III, the contractor will work with the government to integrate high power, highly efficient, good beam quality emitters into a kilowatt class direct diode high energy laser. The direct diode high energy laser developed will be integrated and tested in one of the Army’s high energy laser demonstrators or testbeds.
REFERENCES: 1: Y. Zhao and L. Zhu, "On-chip coherent combining of angled-grating diode lasers toward bar-scale single-mode lasers," 12 March 2012, Vol. 20, No. 6, OPTICS EXPRESS 63752: A. Müller, Dd Vijayakumar, O. B. Jensen, K. Hasler, B. Sumpf, G. Erbert, P. E. Andersen, P. M. Petersen, "16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers," January 2011, Vol. 19, No. 2, OPTICS EXPRESS 12283: B. Liu, Y. Braiman, "Coherent beam combining of high power broad area laser diode array with near diffraction limited beam quality and high power conversion efficiency," 16 December 2013, Vol. 21, No. 25, DOI:10.1364/OE.21.031218, OPTICS EXPRESS 312184: A. Sevian, O. Andrusyak, I. Ciapurin, V. Smirnov, G. Venus, L. Glebov, "Efficient power scaling of laser radiation by spectral beam combining", OPTICS LETTERS, Vol. 33, No. 4, February 15, 20085: O. Andrusyak, V. Smirnov, G. Venus, V. Rotar, L. Glebov, "Spectral Combining and Coherent Coupling of Lasers by Volume Bragg Gratings," IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 15, NO. 2, MARCH/APRIL 20096: L. R. Brewer, "Highly coherent injection-locked laser diode arrays," 20 January 1991, Vol. 30, No. 3, APPLIED OPTICS7: S. M. Redmond, K. J. Creedon,1 J. E. Kansky, S. J. Augst, L. J. Missaggia, M. K. Connors, R. K. Huang, B. Chann, T. Y. Fan, G. W. Turner, A. Sanchez-Rubio, "Active coherent beam combining of diode lasers", March 15, 2011, Vol. 36, No. 6, OPTICS LETTERS8: V. Daneu, A. Sanchez, T. Y. Fan, H. K. Choi, G. W. Turner, and C. C. Cook, "Spectral beam combining of a broad-stripe diode laser array in an external cavity," March 15, 2000, Vol. 25, No. 6, OPTICS LETTERS9: B. Liu, Y. Liu, and Y. Braiman, "Coherent addition of high power laser diode array with a V-shape external Talbot cavity," 8 December 2008, Vol. 16, No. 25, OPTICS EXPRESS 2093510: K. D. Choquette, M. T. Johnson, Z. Gao, B. Thompson, G. Ragunathan, S. T. M. Fryslie, M. P. Tan, D F. Siriani, "Coherent Coupling in Vertical Cavity Laser Arrays (Invited)," 978-1-4577-1504-4/14, 2014 IEEEKEYWORDS: High Power Diodes, Coherent Diode Lasers, High Energy Lasers
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