Small Business Innovation Research/Small Business Tech Transfer
High Energy Single Frequency Yb:YAG Crystalline Fiber Waveguide Master Oscillator Power Amplifier
Project Description
The overall objective is to demonstrate the concept of Yb:YAG crystalline fiber MOPA laser and investigation the technical feasibility toward 50 mJ single frequency MOPA system in the Phase-II research. Onyx Optics crystalline fiber waveguides are made from true rare-earth doped YAG crystals with Adhesive-Free Bond (AFB®) technology. Compared with silica or phosphate glasses, the YAG crystalline fiber waveguides have the following advantages: (i) YAG crystal has at least one order of magnitude lower Stimulated Brillouin scattering (SBS) gain coefficient than silica or phosphate glasses (10-15 to 10-12 vs 10-11 m/W), which directly leads to the SBS free power being at least one order of magnitude higher than the glass fibers; (ii) YAG crystal has much higher thermal conductivity than glass fibers (10.7 vs 1.38 W/m degree C). Therefore, much shorter fiber length that is only about one tenth of the glass fiber can be used for the same pumping conditions and the SBS threshold can be further increased; (iii) Due to the shortening in the fiber length, straight fiber can be practically used for high power amplification. Therefore, large single mode area (LSMA) can be more easily achieved. Considering the high pulse energy requirement in a future LIST mission, only large mode area (LMA) Yb:YAG fibers with core size >40 mm will be fabricated and investigated in the Phase-I research. The fibers will be double clad to increase the pumping power and efficiency, while maintaining near diffraction limit laser beam quality.
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Anticipated Benefits
The proposal is directed towards the construction of a micro-pulsed laser for NASA's Lidar Surface Topography (LIST) mission to globally map the topography of the Earth's solid surface with 5 m spatial resolution and 10 cm vertical precision, as well as the height of overlying covers of vegetation, water, snow, and ice. As pointed out by the LIST study findings, the instrument required to meet the LIST objectives far exceeds those of existing space laser altimeter technologies. Onyx Optics' true crystal fiber technology allows achieving the LIST laser source goals but it also represents a proof-of-principle for a whole family of crystal fiber lasers with different dopants than the presently proposed Yb:YAG that operate at 1.6 um (Er:YAG), at 2 um (Tm:YAG and Ho:YAG) or at 940 nm or 1064 nm (Nd:YAG) and frequency converted to 450 – 500 nm, all with close to diffraction limited beam quality and high pulse energies. These will become superior compact diode pumped sources for a number of NASA missions listed in the solicitation topics.
The proposed pulsed crystal fiber technology at various wavelengths is just as applicable as components for Defense lidar as for NASA. It represents a breakthrough capability for diode pumped solid state lasers that also has medical surgical applications in the 2 um region. The outstanding features of high efficiency, high beam quality and compactness translate into lower cost devices that also will meet great interest in the R&D community of universities and National laboratories. Onyx Optics would sell complete laser systems for R&D use as well as crystal fiber components for researchers to develop their own designs and applications. The high efficiency of the proposed laser systems would result in less energy consumption and thereby, at least in a small way, will save electric energy. More »
The proposed pulsed crystal fiber technology at various wavelengths is just as applicable as components for Defense lidar as for NASA. It represents a breakthrough capability for diode pumped solid state lasers that also has medical surgical applications in the 2 um region. The outstanding features of high efficiency, high beam quality and compactness translate into lower cost devices that also will meet great interest in the R&D community of universities and National laboratories. Onyx Optics would sell complete laser systems for R&D use as well as crystal fiber components for researchers to develop their own designs and applications. The high efficiency of the proposed laser systems would result in less energy consumption and thereby, at least in a small way, will save electric energy. More »
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Primary U.S. Work Locations and Key Partners
| Organizations Performing Work | Role | Type | Location |
|---|---|---|---|
| Onyx Optics, Inc. | Lead Organization | Industry | Dublin, California |
Goddard Space Flight Center
(GSFC)
|
Supporting Organization | NASA Center | Greenbelt, Maryland |
Primary U.S. Work Locations
-
California
-
Maryland
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