Broadly tunable high repetition rate femtosecond optical parametric oscillator

Abstract

We report a new source of femtosecond light pulses which is broadly tunable in the infrared. A singly resonant optical parametric oscillator based on a thin crystal of KTiOPO4 is pumped by intracavity femtosecond pulses at 620 nm from a standard colliding-pulse passively mode-locked dye laser. Oscillation results in stable, continuous outputs of femtosecond pulses at 108 Hz repetition rate and milliwatt average power levels in both signal and idler beams. Here we demonstrate tuning from 820 to 920 nm and 1.90 to 2.54 μm with a single set of mirrors. With multiple sets of mirrors, continuously tunable outputs from ∼0.72 to ∼4.5 μm should be possible, making this a uniquely versatile femtosecond laser source.

High-repetition-rate femtosecond optical parametric oscillator–amplifier system near 3 μm

“…Type-II KTP OPO's were shown to be tunable in the 1.8 -2.5-mm (idler-wave) and the 1.2 -1.4-mm (signal-wave) spectral regions. 15,21,25,28,38 In general, a type-II OPO will have a much broader tuning range than a type-III noncritically phase-matched OPO. However, type-III noncritical phase matching has distinct advantages that make this type of phase matching preferable to type-II phase matching for KTP in the 3-mm region.…”

“…Instead, we chose KTiOPO 4 (KTP) and its isomorphs, which are transparent and tunable in the 3-mm region. 4,15,25,28,32 Although synchronously pumped OPO's do offer the advantage of high repetition rates (70 -80 MHz) and broad tunability, the pulse energy produced (#4 nJ) is low. To perform nonlinear spectroscopic measurements, an OPA is necessary.…”

Recent advances in ultrafast optical parametric oscillator frequency combs

“…Synchronously pumped optical parametric oscillators (OPOs) 1 are a well-established source of ultrashort pulses in the visible to mid-infrared (mid-IR); however, it is only in recent years that their application as a stabilized frequency comb source has been realized and exploited.…”

Optical power limiting in multilayer systems with nonlinear response

“…7 In that work, parametric subharmonic oscillators were suggested as optical limiters with the objective of protecting instrumentation from overload. More recently, Kozlouski 8 and Edelstein, Wachman, and Tang 8,9 have discussed optical limiters in the form of parametric oscillators. The first demonstration of passive limiting by selfdefocusing was performed by Leite, Porto, and Damen in 1967.…”