US 6,191,861 B1 · Femtosecond chirp-free transient absorption method and apparatus

Abstract

A method and apparatus for femtosecond transient absorption comprising phase-sensitive detection, spectral scanning and simultaneous controlling of a translation stage to obtain TA spectra information having at least a sensitivity two orders of magnitude higher than that for single-shot methods, with direct, simultaneous compensation for chirp as the data is acquired. The present invention includes a amplified delay translation stage which generates a splittable frequency-doubled laser signal at a predetermined frequency f, a controllable means for synchronously modulating one of the laser signals at a repetition rate of f/2, applying the laser signals to a material to be sample, and acquiring data from the excited sample while simultaneously controlling the controllable means for synchronously modulating.

Claims17

Dependent claims

A chirp-free method for measuring the transient absorption of a material, said method comprising the steps of:

a. generating pulsed laser beam to serve as a pump beam;
b. generating a broad band pulsed laser beam to serve as a probe beam, said probe beam having a spectrum of wavelengths;
c. passing said pump beam through a means for varying the path length of said pump beam;
d. synchronously modulating said pump beam;
e. directing said modulated pump beam and said probe beam through said material to produce a modulated signal on said probe beam;
f. dispersing said wavelengths of said modulated probe beam;
g. collecting said dispersed wavelengths of said dispersed probe beam;
and
h. simultaneously compensating for chirp between different wavelengths of said dispersed probe beam by varying in a controlled manner said path length of said pump beam to maintain a substantially constant time delay between said pump beam and said different wavelengths of said probe beam.

6 more elements

Dependencies are inferred from the claim text.

Femtosecond chirp-free transient absorption method and apparatus

Life of this patent

Femtosecond chirp-free transient absorption method and apparatus

Life of this patent

Abstract

Claims17