Induced phase modulation of chirped continuum pulses studied with a femtosecond frequency-domain interferometer

Simplified single-shot supercontinuum spectral interferometry

We have experimentally demonstrated a simplified method for performing single-shot supercontinuum spectral interferometry (SSSI) that does not require pre-characterization of the probe pulse. The method, originally proposed by D. T. Vu, D. Jang, and K. Y. Kim, uses a genetic algorithm (GA) and as few as two time-delayed pump-probe shots to retrieve the pump-induced phase shift on the probe [Opt. Express26, 20572 (2018)]. We show that the GA is able to successfully retrieve the transient modulations on the probe, and that the error in the retrieved modulation decreases dramatically with the number of shots used. In addition, we propose and demonstrate a practical method that allows SSSI to be done with a single pump-probe shot (again, without the need for pre-characterization of the probe). This simplified method can prove to be immensely useful when performing SSSI with a low-repetition-rate laser source.

Single-shot chirped-pulse spectral interferometry used to measure the femtosecond ionization dynamics of air

A novel interferometry technique is presented by which, in one shot, one can measure phase changes with a resolution of tens of femtoseconds while extending the measurement over picoseconds or even longer. The method is based on spectral (frequency-domain) interferometry with a pair of linearly chirped pules as probes. With this technique we obtained single-shot measurements of the rapid phase changes induced by optical field ionization of air. This allowed us to calculate the time profile of the electron density created by an intense short laser pulse.

Spectral interferometry as an alternative to time-domain heterodyning

A novel method of time resolving the amplitude and phase of a transient nonlinear-optical polarization, based on Fourier transformation of a spectral interference pattern, is discussed. We show that with this technique the delay at which the polarization is generated can be retrieved. The method is demonstrated in a transient four-wave-mixing experiment on a dye solution.

Measurement of photon echoes by use of femtosecond Fourier-transform spectral interferometry

Using Fourier-transform spectral interferometry, we demonstrate the measurement of both amplitude and phase of photon echoes in GaAs multiple-quantum-well structures. The complete measurement of the electric field thus achieved makes possible the determination of the corresponding Wigner spectrograms.

Femtosecond Sagnac interferometer for phase spectroscopy

We developed a novel femtosecond Sagnac interferometer that enables us to take single-shot measurements of both the difference transmission and the difference phase spectra. Owing to the excellent stability of the Sagnac interferometer, a difference phase spectrum was obtained with a high phase change sensitivity of ~lambda/100 after a 1000-shot accumulation. The spectral range, wavelength, and time resolution were 530-650 nm, 1 nm, and 200 fs, respectively.

Measurement of the Raman gain spectrum of optical fibers

The stimulated Raman gain spectrum of optical fibers has been measured down to 6 cm(-1) by means of short pulses. Results for parallel and perpendicular polarizations are reported. With this technique, we observe spectral oscillations arising from a Brillouin mediated coupling between cw and pulsed light.