Method and apparatus for measuring a time delay between pairs of pulses from laser pulse sequences, and applications thereof

Inventors

Weigel, Alexander • BUBERL, Theresa • Krausz, Ferenc • Pupeza, Ioachim

Assignees

Ludwig-Maximilians-Universität München • Max-Planck-Gesellschaft zur Förderung der Wissenschaften eV

Abstract

A laser pulse sequence measuring method for measuring a delay between a pair of pulses from two laser pulse sequences (1, 2), comprises the steps of creating a first laser pulse sequence (1) of first laser pulses (1A) and a second laser pulse sequence (2) of second laser pulses (2A), and generating a delay signal (3) which represents the delay between the pair of pulses from the first and second laser pulse sequences (1, 2), wherein the step of generating the delay signal (3) includes creating intra-pulse difference frequency generation (IPDFG) pulses (4) by applying intra-pulse difference frequency generation to the first laser pulses (1A) in a difference frequency generation (DFG) medium (21), providing phase-stable reference waveforms (5) based on the IPDFG pulses (4), and electro-optic sampling (EOS) of the electric field of the phase-stable reference waveforms (5) with sampling pulses (6) in an EOS medium (22), wherein the sampling pulses (6) are created based on the second laser pulses (2A), for generating an electro-optic sampling (EOS) signal (7), wherein the delay signal (3) is obtained from the EOS signal (7). Furthermore, a spectroscopic measuring method, a laser pulse sequence measuring apparatus (100) and a spectroscopic measuring apparatus are described.

Core Innovation

The invention relates to a laser pulse sequence measuring method and apparatus for tracking a delay between a pair of pulses from two laser pulse sequences. The delay comprises a temporal separation between the pulses, and the invention generates a delay signal that is a quantitative measure of the delay between the pulse pairs. The delay signal is obtained from an electro-optic sampling signal derived from sampling pulses created based on the second laser pulses.

To generate the delay signal, the method creates intra-pulse difference frequency generation pulses by applying intra-pulse difference frequency generation to the first laser pulses in a difference frequency generation medium. Based on the intra-pulse difference frequency generation pulses, the method provides phase-stable reference waveforms. The phase-stable reference waveforms are electro-optically sampled by sampling pulses in an electro-optic sampling medium to generate the electro-optic sampling signal.

The disclosed approach yields delay tracking that is independent of carrier-envelope phase relationships. It is extended to time-domain spectroscopy by using the derived delay signal to reconstruct or create a delay axis for spectroscopic measurements using frequency-detuned pulse trains. It is also extended to active repetition-frequency locking by providing feedback control based on the delay signal.

Claims Coverage

The partial content identifies two independent claims: a measuring method claim and a corresponding apparatus claim. Each independent claim is built around the same core inventive sequence: intra-pulse difference frequency generation pulses to provide phase-stable reference waveforms, electro-optic sampling using sampling pulses derived from a second pulse sequence, and obtaining a quantitative delay signal from the electro-optic sampling signal.

Across both independent claims, the delay between pulses from two laser pulse sequences is tracked by converting the first pulse sequence into intra-pulse difference frequency generation pulses, using those to form phase-stable reference waveforms, and then generating a quantitative delay signal from an electro-optic sampling signal produced with sampling pulses derived from the second pulse sequence.

Stated Advantages

Documented Applications