Generation of intense 100 fs solitons tunable from 2 to 43 μm in fluoride fiber

Abstract

There is great interest in sources of coherent radiation in the mid-wave infrared (3–5 μm), and instruments based on fiber can offer major practical advantages. This range, and much broader, can be covered easily by supercontinuum generation in soft glass fibers, but with low power spectral density. For applications that require intense ultrashort pulses, fiber sources are quite limited. In this Letter, we report a fiber-based system that generates 100 fs pulses with 5 nJ energy, continuously wavelength-tunable over 2–4.3 μm through the soliton self-frequency shift (SSFS) in fluoride fibers. The pulse energies are 2 orders of magnitude higher than those previously achieved by SSFS, around 3 μm, and the range of wavelengths is extended by 1000 nm. Peak power ranges from 20 to 75 kW are achieved across the tuning range. Numerical simulations are in good agreement with the experimental results, and indicate the potential for few-cycle soliton generation out to 5.6 μm. Fiber-integrated sources of femtosecond pulses tunable across this region should be valuable for mid-infrared applications.