US 2026/0121369 A1 · MEASUREMENT AND CONTROL OF THE FREQUENCY OF AN OPTICAL SIGNAL

Abstract

The disclosure relates to a method for determining the frequency of an optical signal. The method is intended to enable precise frequency determination with improved dynamics compared to the prior art. It should be possible to unequivocally determine the frequency of the optical signal over a wide frequency range. For this, the method comprises the following steps: Generation of an in-phase (I) and a quadrature signal (Q) by heterodyne optical quadrature detection, wherein the optical signal is superimposed with an optical reference signal whose spectrum is an optical frequency comb, and the in the process resulting beat signals are detected, converting the analog in-phase (I) and quadrature signals (Q) into digital signals with a sampling rate equal to the frequency spacing (fR) between adjacent spectral lines of the frequency comb, and determining the frequency spacing (fL) between the frequency (vCW) of the optical signal and the frequency (vFC) of one of the spectral lines of the frequency comb by processing the digital in-phase and quadrature signals. The disclosure also relates to a method for controlling the frequency (vCW) of an optical signal, as well as a laser system.

Claims16

Dependent claims

Method for determining the frequency of an optical signal, comprising the following steps:

Generation of an in-phase (I) and a quadrature signal (Q) by heterodyne optical quadrature detection, wherein the optical signal is superimposed with an optical reference signal whose spectrum is an optical frequency comb, and the in the process resulting beat signals are detected, converting the analog in-phase (I) and quadrature signals (Q) into digital signals with a sampling rate equal to the frequency spacing (fR) between adjacent spectral lines of the frequency comb, and
determining the frequency spacing (f) between the frequency of the optical signal and the frequency (vFC) of one of the spectral lines of the frequency comb by processing the digital in-phase and quadrature signals.

Laser system, with

a first, for example continuously emitting (cw) laser radiation source (1), intended to emit an optical signal at a frequency (vCW),
a second laser radiation source, for example a short-pulse laser radiation source (2), intended to emit an optical reference signal whose spectrum is an optical frequency comb, wherein the distance between adjacent spectral lines of the frequency comb is equal to a repetition rate (fR),
an optical quadrature detector (3) with two photodetectors (PD1, PD2), intended to detect beat signals generated on the photodetectors (PD1, PD2) by superimposing the optical signal with the optical reference signal as in-phase and quadrature signals according to the principle of heterodyne quadrature detection,
two analog-to-digital converters (ADC1, ADC2) associated with the photodetectors (PD1, PD2), intended to convert the analog in-phase and quadrature signals (I, Q) into digital, time-discrete signals at a sampling rate equal to the repetition rate (fR), and
a digital signal processing device (4) designed to determine the frequency difference (fL) between the frequency (vCW) of the optical signal and the frequency (vFC) of one of the spectral lines of the reference signal by processing the digital in-phase and quadrature signals.

2 more elements

Dependencies are inferred from the claim text.

Measurement and control of the frequency of an optical signal

Life of this patent

Measurement and control of the frequency of an optical signal

Life of this patent

Abstract

Claims16