Convert 1um Ultrafast Fiber Laser to 2um, and Pulses Less than 100Fs

Ultrafast mid-IR sources are necessary for seeding the E-SASE FELs (enhanced self-amplified spontaneous emission free electron lasers) used at DOE facilities. These sources need to have ~mJ energies and very high (100 kHz) repetition rates at ~ 2-2.2 µm wavelength. While commercially available Ti:sapphire/OPA systems can certainly deliver mJ energy pulses at 2µm, they lack the high repetition frequency required for this application. Also, Ti:sapphire systems have large footprints and cost 100s of thousands of dollars. Therefore, this project will develop a method for using an ultrafast, 1µm amplified fiber laser system and an OPA for amplification at high repetition rates in cryo-cooled Cr:ZnS. In Phase I, a 1µm fiber light will be frequency converted to ~2µm in a white-light-seeded OPA, which will more than double the spectrum. Cross polarization wave generation (XPW) will be used to further broaden the bandwidth of the 2µm. The output will then be ready for final amplification in Cr:ZnS. Phase II will involve building a prototype and testing viability in a cryo-cooled Cr:ZnS system. Commercial applications and other Benefits as described by the awardee: The method should allow the current Ti:sapphire system to be replaced with a significantly lower-cost solution. Other benefits include the production of eye-safe high-average-power ultrafast (<50 fs) laser systems at a reasonable price, and more compact high-harmonic systems for soft x-ray generation.