Generation of intense ultrabroadband optical pulses by induced phase modulation in an argon-filled single-mode hollow waveguide

Abstract

We experimentally demonstrate the generation of intense ultrabroadband optical pulses whose spectrum ranges from 300 to 1000 nm (700-THz bandwidth) with a well-behaved spectral phase and 23-mJ pulse energy by a novel, simple setup utilizing induced phase modulation (IPM) in an argon-f illed single-mode hollow waveguide. Fundamental as well as second-harmonic pulses produced by one common femtosecond pulse from a Ti:sapphire laser-amplif ier system are copropagated in the hollow waveguide. The effect of the delay time between the two input pulses on the IPM spectral broadening is clarif ied and confirmed to agree with the theoretical result. It is found that the compressed pulse duration from this pulse is 1.51 fs if its phase is completely compensated for. 

Comparison between Finite-Difference Time-Domain Method and Experimental Results for Femtosecond Laser Pulse Propagation

“…The spectrabroadening by the induced-phase modulation (IPM) is one of these methods. There have been some reports of experiments on ultrabroadband-pulse generation using IPM in a silica fiber (Xu et al, 1999), (Karasawa et al, 2001b), (Shibata et al, 2002), (Yamashita et al, 2004) and an Ar-gas-filled hollow fiber, (Karasawa et al, 2000b) and also on optical pulse compression by nonlinear chirp compensation. (Yamashita et al, 2004) For these experiments on generating few-optical-cycle pulses, characterizing the spectral phase of ultrabroadband pulses analytically as well as experimentally is very important.…”

“…In addition, because of the high repetition rate and pulse intensity stability in particular, ultrabroadband supercontinuum light generation and few-optical-cycles pulse generation by nonlinear pulse propagation in photonic crystal fibers (Ranka et al, 2000) and tapered fibers (Birks et al, 2000), which are both made of silica, have attracted much attention. We have extended the FDTD method, (Nakamura et al, 2002b) with nonlinear polarization P NL involving the Raman response function (JGTH-algorithm) to 12 fs ultrabroad-band-pulse propagation in a silica fiber with the consideration of linear polarization P L , including all exact Sellmeier-fitting values of silica with three resonant frequencies, in order to compare the calculation results with our experimental results (Nakamura et al, 2002a), (Karasawa et al, 2000b). In this section, we describe the details of the calculation algorithm of the extended FDTD method (Nakamura et al, 2002b) and we also compare the extended FDTD method (Nakamura et al, 2002b) with BPM by applying the split-step Fourier (SSF) method, which is the solution of a modified generalized nonlinear Schrödinger equation (MGNLSE) , with SVEA, precisely considering the same Raman response function as that of the extended FDTD method, and up to the fifth-order dispersion.…”

Comparison between theory and experiment of nonlinear propagation for a-few-cycle and ultrabroadband optical pulses in a fused-silica fiber

“…Thus, when the delay time is fs, both pulses overlap near the fiber exit end. For the capillary fiber IPM using the fundamental and the second-harmonic pulses, we have analytically [6] and experimentally shown [7] that the spectrum overlapping becomes largest when both pulses meet near the fiber exit end. The present results indicate that a similar tendency holds for the fused-silica fiber.…”

“…Recently, we have proposed to use both induced-phase modulation (IPM) and self-phase modulation (SPM) to generate ultrabroadband optical pulses using a single-mode fused-silica fiber [3]- [5] and a capillary fiber filled with noble gas [6], [7]. For the fused-silica fiber, the Raman effect may become important when the pulse duration is close to the Raman response time [8], [9].…”

Spatial light modulator with an over-two-octave bandwidth from ultraviolet to near infrared

“…More recently, 2.6 fs, 1.3 cycle pulses (1.4 GW peak power) were generated by using the same compensation technique for pulses ultrabroadened by induced-phase modulation (IPM) as well as SPM [3]. Although the pulse spectrum has been broadened over the octave ranging from 300 to 1000 nm by IPM as well as SPM [4], which corresponds to 1.5 fs, 0.9 cycle transform-limited pulses [4], further shortpulse compensation has not succeeded owing to the bandwidth limitation resulting from the ultraviolet (UV) absorption by the liquid crystal. Therefore, the LC-SLM operating over the UV-to-near-infrared (UVto-NIR) range is strongly desired.…”