All-optical retrieval of the global phase for two-dimensional Fourier-transform spectroscopy

A combination of spatial interference patterns and spectral interferometry are used to find the global phase for non-collinear two-dimensional Fourier-transform (2DFT) spectra. Results are compared with those using the spectrally resolved transient absorption (STRA) method to find the global phase when excitation is with co-linear polarization. Additionally cross-linear polarized 2DFT spectra are correctly phased using the all-optical technique, where the SRTA is not applicable.Comment: 6 pages, 7 figures, journal publicatio

Sub-picosecond phase-sensitive optical pulse characterization on a chip

he recent introduction of coherent optical communications has created a compelling need for ultrafast phase-sensitive measurement techniques operating at milliwatt peak power levels and in timescales ranging from sub-picoseconds to nanoseconds. Previous reports of ultrafast optical signal measurements in integrated platforms include time-lens temporal imaging on a silicon chip and waveguide-based frequency-resolved optical gating (FROG). Time-lens imaging is phase-insensitive, and waveguide-based FROG methods require the integration of long tunable delay lines, which is still an unsolved challenge. Here, we report a device capable of characterizing both the amplitude and phase of ultrafast optical pulses with the aid of a synchronized incoherently related clock pulse. It is based on a novel variation of spectral phase interferometry for direct electric-field reconstruction (SPIDER) that exploits degenerate four-wave mixing in a CMOS-compatible chip. We measure pulses with a peak power of 1 THz, and up to 100 ps pulsewidths, yielding a timeg-bandwidth product of >100