# US 2019/0356103 A1 · Optical frequency comb generator with carrier envelope offset frequency detection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0356103 A1 - Document ID: US20190356103A1 - Status: Published application - Kind: A1 - Application number: 16/474,391 - Filed: 2018-01-05 - Published: 2019-11-21 - Earliest claimed: 2017-01-05 - Assignees: Ipg Photonics Corporation - Applicants: Ipg Photonics Corporation - Inventors: Sergey VASILYEV - Web page: https://patentgrep.com/patent/US20190356103A1 ## CPC - H01S 3/0092: {Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity (nonlinear frequency conversion per se G02F1/35)} - G01J 11/00: Measuring the characteristics of individual optical pulses or of optical pulse trains - G02F 3/026: {based on laser effects} - H01S 3/1095: {self doubling, e.g. lasing and frequency doubling by the same active medium} - H01S 3/1112: Passive mode locking - H01S 3/1307: {Stabilisation of the phase} - G02F 2203/56: Frequency comb synthesizer - H01S 3/0014: {Monitoring arrangements not otherwise provided for (photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003)} - H01S 3/08086: {Multiple-wavelength emission} - H01S 3/1312: {by controlling the optical pumping} - H01S 3/1623: {chromium, e.g. Alexandrite} - H01S 3/1628: {characterised by a semiconducting matrix} - H01S 3/1685: {Ceramics} - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract The present invention provides systems and methods for optical frequency comb generation with self-generated optical harmonics in mode-locked lasers for detecting the carrier envelope offset frequency. The mode-locked laser outputs an optical frequency comb and a harmonic output. The harmonic output provides an optical heterodyne resulting in a detectable beat note. A carrier envelope offset frequency detector detects the beat note and generates an optical frequency comb signal. The signal can be used to stabilize the optical frequency comb output. ## Claims ### Claim 1 An optical frequency comb generator system comprising, a mode-locked laser that oscillates within a fundamental optical frequency comb spectrum and simultaneously generates an optical frequency comb output and a heterodyne output, the heterodyne output comprising a first spectral component from a first auxiliary optical frequency comb and a second spectral component from a second auxiliary optical frequency comb, at least one of the first and second auxiliary optical frequency combs comprising an optical harmonic of the fundamental optical frequency comb, the optical frequency comb output characterized by a carrier envelope offset frequency, wherein the mode-locked laser comprises a laser pump source and a femtosecond (fs) oscillator; and a carrier envelope offset frequency detector configured to receive and detect the first and second spectral components, wherein the carrier envelope offset frequency detector is further configured to generate a signal corresponding to the carrier envelope offset frequency. ### Claim 2 The system as in one of the above claims, the fs oscillator being configured with a nonlinear laser medium, wherein the mode-locked laser generates the optical frequency comb output and self-generates at least one optical harmonic in the nonlinear laser medium. ### Claim 3 The system as in one of the above claims, wherein the mode-locked laser operates such that the laser output further comprises an optical heterodyne with a beat note frequency that corresponds to the carrier envelope offset frequency, wherein the carrier envelope offset frequency detector detects the carrier envelope offset frequency. ### Claim 4 The system as in one of the above claims, wherein the first and second auxiliary optical frequency combs partially spectrally overlap. ### Claim 5 The system as in one of the above claims, wherein the first and second auxiliary optical frequency combs comprise the fundamental and any other harmonic optical frequency combs. ### Claim 6 The system as in one of the above claims, wherein the first and second auxiliary optical frequency combs comprise any two distinct harmonic optical frequency combs. ### Claim 7 The system as in one of the above claims, further comprising at least one spectral broadening element operative to broaden at least one of the first and second auxiliary optical frequency combs such that the first and second auxiliary optical frequency combs overlap, wherein the spectral broadening element is located between the fs oscillator and the carrier envelope offset frequency detector. ### Claim 8 The system as in one of the above claims, the mode-locked laser further comprising a resonator cavity tailored for increased output at one or more optical harmonics. ### Claim 9 The system as in one of the above claims, further comprising at least one spectra filter configured to modify the spectral content of the heterodyne output. ### Claim 10 The system as in one of the above claims, wherein the carrier envelope offset frequency detector is configured to provide a signal used to control the carrier envelope offset frequency and thereby stabilize the optical frequency comb output. ### Claim 11 (depends on 1) The system as in claim 1, wherein the mode-locked laser further comprises a Kerr-lens mode-locked mid-IR fs oscillator that is configured with a TM:II-VI type material with high second and third order nonlinearity and a polycrystalline structure, wherein the laser oscillator provides three-wave mixing via a random quasi-phase matching process. ### Claim 12 In a mode-locked laser based system with an optical frequency comb output and a heterodyne output, the optical frequency comb output characterized by a carrier envelope offset frequency, a method of providing an optical frequency comb comprising; simultaneously generating an optical frequency comb output and a heterodyne output with a mode-locked laser; detecting a beat note between spectral components of respective first and second auxiliary optical frequency combs in the heterodyne output; and generating a signal corresponding to the carrier envelope offset frequency based on the detected beat note. ### Claim 13 (depends on 12) The method as in claim 12, further comprising measuring the carrier envelope offset frequency. ### Claim 14 (depends on 12) The method as in claim 12, further comprising; detecting a beat note with a carrier envelope offset frequency detector; and providing a carrier envelope offset frequency signal to a carrier envelope offset frequency control system to stabilize the carrier envelope offset frequency. ### Claim 15 A method of detecting a carrier envelope offset frequency in a Kerr lens mode-locked mid-IR polycrystalline Cr:ZnS oscillator based laser system with a self-generating harmonic output, the method comprising; simultaneously generating an optical frequency comb output and one or more optical harmonics directly in the Cr:ZnS material; detecting a heterodyne beat note between a first spectral component and a second spectral component of respective first and second auxiliary optical frequency combs that comprise at least one of the one or more optical harmonics, and generating a signal corresponding to the carrier envelope offset frequency based on the detected beat note.