100 W green laser

Period of Performance: 02/17/2015 - 11/16/2015


Phase 1 SBIR

Recipient Firm

Q Peak, Inc.
135 South Road Array
Bedford, MA 01730
Firm POC
Principal Investigator


Statement of the problem or situation that is being addressed For synchronous photoinjection of GaAs photoemission guns a high-average-power, green-laser light source, with an RF-pulse repetition rate in the range of 0.5 to 3 GHz, is required to advance fundamental accelerator technology and its application to nuclear physics scientific research. The efficiency of a GaAs photocathode degrades over time. In order to maintain a constant photoemission, the output power in the laser used in the photoinjector has to be increased. A 100-W green laser operating at 532 nm could provide uninterrupted photoemission for up to 4 days. General statement of how this problem is being addressed. Q-Peak proposes to develop a novel gain switched Yb-doped fiber laser pump, frequency-doubled architecture that would produce 30-60 ps pulse trains at 0.5 to 3 GHz repetition rate. The fiber laser would deliver 100 W of 532 nm light combining a simple technique of generating short pulses with a power amplifier. At high-average-output powers, the low thermal lensing of fiber laser together with negligible nonlinear effects provides superior performance to other solid state bulk material schemes. What is to be done in Phase I? 1. Hold kick-off meeting 2. Model, design, and build a 100-W gain switched Yb-doped fiber laser pump 3. Test the long term reliability of the fiber pump laser 4. Frequency double the 100-W fiber laser to generate 20-30 W of green light 5. Test the long term reliability of the green laser 6. Design and model an amplifier architecture to reach 200-W of IR power 7. Design and model SHG efficiency to obtain 100-W of green light 8. Prepare final report Commercial Applications and Other Benefits Our proposed laser fulfills an important near-term need as a source used in photoinjector applications for linear accelerators and free electron lasers. In addition to its use in the photoinjector for a GaAs photoemission gun, the laser also has application in the Compton polarimetry and electro-cooling in the Relativistic Heavy Ion Collider (RHIC) as well as in time-resolved spectroscopy, terahertz generation, and materials processing. Accelerators are also used as versatile x-ray sources for a wide range of applications, such as biochemistry, condensed matter, materials science and diagnostic medicine. Advances in fundamental accelerator technology may allow accelerators for these purposes to be built with greater capability while being more compact and less expensive. Key Words Gain switched, fiber lasers, frequency doubling, photoinjector, electrons Summary for Members of Congress The laser that is being proposed in this program will be one of the key components needed to advance accelerator science and technology. Long term applications are in the fields of medicine, material processing and defense.