Time-to-frequency converter for measuring picosecond optical pulses

Abstract

We present a new technique for measuring the intensity I(t) of optical pulses using a temporal optical system. A diffraction grating pair followed by a microwave-driven, optical phase modulator configured as a time lens is used to uniquely map the pulse shape from the time domain to the frequency domain, allowing measurement of the pulse shape with a spectrometer. We discuss the theory of operation and present experimental results illustrating 3 ps time resolution.

Time-domain Fresnel-to-Fraunhofer diffraction with photon echoes

“…Experimental demonstrations of this duality that have been reported so far have dealt with picosecond laser pulses. A grating pair was used as a dispersive line, and an electro-optic phase modulator 8,9 or an optical nonlinear wave-mixing process 10 as a time lens. The time-bandwidth product of an electro-optic time lens is given by the peak phase deviation of the modulator and is therefore quite poor, below 100, which is not satisfactory for optical signal processing.…”

Time-dependent spectrum of a single photon and its positive-operator-valued measure

“…Whereas measuring the frequency of light has been relatively straightforward since Newton's days, measuring the time of arrival (on, say, a picosecond timescale) tends to be much harder. One nice way to achieve a high-resolution time measurement is to measure the frequency after first sending the photon through a time-to-frequency converter [17][18][19][20][21][22]. Here one first lets the photon propagate through a dispersive element that multiplies the spectral amplitude of the photon with a phase factor exp(−iαω 2 /2), with α a constant, and subsequently one applies a time-dependent phase modulation that multiplies the temporal amplitude with a similar phase shift exp(−iβt 2 /2) in the time-domain.…”

The Application based on Fourier Transform in Time Lens

“…In recent years, people carried on the thorough research of time lens both at home and abroad. The theory of time lens continuously perfect [3][4][5][6], and it has broad application prospects such as the optical pulse compression and amplification [7], transformation of time domain, frequency domain [8], optical signal detection and process [9][10], etc..…”