Low-Noise Femtosecond SESAM Modelocked Diode-Pumped Cr:ZnS Oscillator

Abstract

Cr-doped ZnS and ZnSe are excellent gain mediums for high power and broadband ultrashort pulse generation in the 2 – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3~\mu \text{m}$ </tex-math></inline-formula> wavelength range. SESAM modelocked Cr:ZnS oscillators have the advantage of reliable, self-starting passive modelocking. We present a diode-pumped, SESAM modelocked Cr:ZnS oscillator delivering ultrashort pulses of 189 fs at 550 mW average output power with a repetition rate of 435 MHz with low relative intensity noise (RIN) and timing jitter. We measured an integrated RIN of 0.05% within a frequency span of [10 Hz, 5 MHz] dominated by the 1560-nm pump diode, and a very low integrated timing jitter of 10.9 fs [2 kHz, 10 MHz]. This type of laser source benefits not only from very low noise but also from reduced complexity and cost due to direct diode pumping, which is suitable for many applications such as spectroscopy, ranging, and frequency conversion.