SBIR-STTR Award

We propose to combine a strecherless fiber amplification technique developed by KMLabs that produces sub-200 fs, 0.1 mJ-class pulses with a coherent pulse stacking technique developed at the University of Michigan to obtain mJ-class, femtosecond output pulses without relying on traditional chirped-pulse-ampltification. The coherent pulse stacking technique coherently adds multiple lower-energy pulses together and has been demonstrated up to enhancement factors of 9x with a clear path to enhancement of greater than 80x. Such a source would provide high energy, ultra short pulse pulses from a fiber laser platform without the disadvantages of bulky diffraction-grating stretcher and compressors. This advancement would further ruggedize high-energy ultrashort pulse laser devices for mobile deployment as well as opening scientific and commercial applications that have traditionally relied on amplification in bulk laser media because of the pulse energy and pulse duration limitations of fiber lasers.

Benefit:
The successful completion of this project would give KMLabs a market-leading technology for Yb fiber-based sources. KMLabs excels at bringing innovative technical advances to market, and our product are often the highest-performing in their class because of the use of innovative technology. This lasers system, in particular, would have the ability to replace expensive and unreliable bulk crystal laser systems (typically Ti:sapphire) with a fiber-based platform of high reliability and ruggedness. One of the most important commercial applications for this laser would be in wavelength conversion, where the fundamental light is shifted to a different wavelength that is inaccessible with typical laser systems. KMLabs would leverage our phase-matched high harmonic generation IP to turn this laser into a 100-200 nm source with multi-watt output. Such a laser would revolutionize the wafer inspection tools currently used by chip makers. This will help drive production costs down (along with the cost of your cell phone) and increase reliability.

Keywords:
Ultrashort pulse laser, Ultrashort pulse laser, non-chirped pulse amplification, fiber amplifier, Coherent combining, coherent pulse stacking, femtosecond, fiber laser

KMLabs will construct a stretcher-less mJ-class ultra-short pulsed laser system at repetition rates in excess of 20 kHz. Our proposed laser system combines coherent pulse stacking technology developed at the University of Michigan by Prof. A. Galvanauskas with KMLabs stretcher-less fiber amplification technology. Using a GHz class fiber oscillator and frequency comb stabilization techniques, we will pulse stack a burst of pulses containing 1 mJ of energy in a cascade of Gires-Tournois Interferometer cavities. Following the pulse stacker, a small footprint grating compressor, roughly the size of a deck of cards, will de-chirp the pulse to below 200 fs, achieving 3.5 GW of peak power.

Benefit:
The first product that would be developed based on this work would have a market leading pulse energy and average power for sub-200 fs pulses. Target specifications for this product, in line with the specifications contained in this proposal here would be: pulse energy of 0.1-1 mJ, average power of 50 W, and pulse duration

Keywords:
coherent pulse stacking, fiber amplifier, ultra-short pulsed laser