N101-009 TITLE: Novel Laser Gain Media

TECHNOLOGY AREAS: Sensors, Electronics

ACQUISITION PROGRAM: PMA 264, Air ASW Systems; AIR-290

OBJECTIVE: Develop high efficiency laser gain media with fundamental transitions or frequency multiplied transitions in the 20,300 cm-1 to 21,800 cm-1 region

DESCRIPTION: Currently, fundamental research into laser gain media with transitions suitable for stimulated emission in the 20,300 cm-1 to 21,800 cm-1 region is insufficient. State of the art gain media with transitions in this region include Ti:Sapphire (doubled), Nd:YAG (946nm doubled) [1-3], and Cr:LiSAF (doubled) [4]. However, generation of light in the desired waveband is typically achieved with multiple stage lasing/amplifying/nonlinear wavelength shifting. Such a multistage process is inherently inefficient. Hot metal vapor, and chemical lasers typically have operational issues due to the desire to avoid HAZMAT, hot gases and liquids within the aircraft. Liquid lasers based on flowing liquid have additional complications due to strict plumbing requirements on aircraft. Additionally, areas of operation may include highly humid environments making the use of hygroscopic and cryogenic crystals challenging.

Gain media with fundamental transitions or transitions that can be frequency multiplied into this region are sought. Gain media for solid state and fiber lasers are preferred, however alternate laser media will be considered. Gain media must be amenable to pulsed laser design; proposals for gain media should address the potential for the material to be used in a laser system capable of meeting all parameters simultaneously. Gain media should have the potential to be developed into ruggedized airborne military laser operating in a harsh environment. Gain media should support maximum of nanosecond pulses (~20 ns), and pulsed operation in 500 Hz to 1 kHz range. All proposals should discuss practical considerations driving minimum and maximum pulse rate and effect of repetition rate on energy per pulse of theoretical laser based on gain media. It should have fundamental transition and high energy per pulse potential as measured in the 20,300 cm-1 to 21,800 cm-1 region. (Threshold: 10 mJ/pulse, Objective: 20 mJ/pulse). The high damage threshold should be consistent with laser output of 10 W average power and 10 mJ at 1 kHz repetition rate. Narrow laser linewidth (Threshold: 0.1 nm, Objective: 0.01nm); lasing transition without cavity can be broad. Gain media should have pump bands that can be COTS diode or COTS laser pumped.

PHASE I: Determine feasibility of proposed gain media achieving all parameters. Define plan for the development of the proposed media into laser grade material.

PHASE II: Develop, demonstrate and validate prototype laser grade gain media.

PHASE III: Build, characterize, and deliver laser using Phase II gain media. It is anticipated that the small company may need to partner with laser manufacturer.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Oceanographic bathymetry systems for survey and exploration work would benefit greatly from gain media with a more efficient transition in the in the 20,300 cm-1 to 21,800 cm-1 range. The gain media proposed in this SBIR will remove a critical impediment to more efficient laser transmitters in this wavelength.

REFERENCES:
1. M. E. Thomas, A. K. Carr, D. Limsui, and J. C. Huie, "Optical Properties of Nd Doped and Undoped Polycrystalline YAG", Proc. of SPIE Vol. 6545 65450F, 2007.

2. Theresa J. Axenson, Norman P. Barnes, and Donald J Reichle, "946 nm diode pumped laser produces 100 mJ", Proceedings of SPIE, Vol 4153, 2001.

3. Theresa J Axenson, "High Energy Q-switched 0.946 um solid state diode pumped laser", J. Optical Society of America B, Vol 19, No 7, 2002.

4. Stephen A Payne, et al, "Properties of Cr:LiSrAlF6 crystals for laser operation", Applied Optics, Vol 33, No 24, 20 August 1994; http://adsabs.harvard.edu/abs/1994ApOpt..33.5526P

5. Optical Propagation in Linear Media, Michael E. Thomas, Oxford University Press, 2006.

6. Absorption and Scattering of Light by Small Particles, Craig F. Bohren, Donald R. Huffman, Wiley-VCH, 2004.

7. Solid State Laser Engineering, W. Koechner, Springer Science, 2006.

KEYWORDS: Gain Media; Solid State Gain Media; Oceanographic Lidar; Optical Communication; Underwater Optical Communication; Fiber Laser

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between November 12 and December 9, 2009, you may talk directly with the Topic Authors 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 December 10, 2009, when DoD begins accepting proposals for this solicitation.

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