15:00 〜 15:15
▼ [6p-S45-8] Passively CEP-stabilized, over one-octave-bandwidth infrared pulses amplified in a BBO crystal by 708-nm femtosecond pump pulses
キーワード：Ultrafast nonlinear optics, Parametric oscillators and amplifiers
We generate ultrabroadband, self-phase-stabilized, infrared pulses centered at wavelength of 1.72 um by a 708-nm pumped two-stage optical parametric amplification (OPA) operating at degeneracy for beta-barium borate (BBO) crystals. The pump source is a lab-built Ti:sapphire-based chirped-pulse amplification (CPA) system composed of a regenerative amplifier and a four-pass amplifier. Via this two-stage CPA system, an intense ultrashort pump pulse with energy of 1.8 mJ, duration of 60 fs, and repetition rate of 200 Hz is generated. The pump wavelength is specifically tuned at 708 nm for the realization of the broadest gain bandwidth in the BBO crystals of the OPA system. The combination of the 708-nm pump source and two-stage amplification in the OPA enables the generation of more than one-octave spectral bandwidth ranging from 1 to 2.2 um, corresponding to a transform-limited pulse duration of 5.1 fs (0.9 optical cycle). On the other hand, the resulting pulse is passively carrier-envelope-phase (CEP) stabilized since it is the difference frequency generation between the pump and the signal arising from the same source. To determine the stability of CEP, we performed a long-term CEP measurement of the amplified pulses using an f-to-2f interferometer. The CEP was directly measured without additional spectral broadening due to the ultrabroad spectral bandwidth we have obtained. The CEP stability is measured to be ~990 mrad (rms) over 1 min.