Laser oscillator system and method for generating light pulses

Patent metadata

Field	Value
Publication number	US-2024106184-A1
Application number	US-202318527819-A
Country	US
Kind code	A1
Filing date	Dec 4, 2023
Priority date	Jun 8, 2021
Publication date	Mar 28, 2024
Grant date	—

Abstract

A laser oscillator system includes a resonator cavity for confining an intra-cavity laser beam. The laser oscillator system further includes a Cr-doped II-VI gain medium arranged within the resonator cavity and an imaging unit forming part of the resonator cavity. The imaging unit is configured to decouple a spot size of the intra-cavity laser beam at the gain medium from an intra-cavity length of the resonator cavity. Moreover, the resonator cavity and the imaging unit are configured such that the laser oscillator system emits laser pulses at a repetition rate of 50 MHz or less. Further, a laser system and methods for generating light pulses having spectral components at a wavelength of at least 2 μm are disclosed.

First claim

1 . A laser oscillator system comprising:
a resonator cavity configured to confine an intra-cavity laser beam; a Cr-doped II-VI gain medium arranged within the resonator cavity; and an imaging unit forming part of the resonator cavity, wherein the imaging unit is configured to decouple a spot size of the intra-cavity laser beam at the gain medium from an intra-cavity length of the resonator cavity, and wherein the resonator cavity and the imaging unit are configured such that the laser oscillator system emits laser pulses at a repetition rate of 50 MHz or less.

2 . The laser oscillator system according to claim 1 , wherein the imaging unit is configured to provide a tunable intra-cavity length.

3 . The laser oscillator system according to claim 2 , wherein the spot size of the intra-cavity laser beam at the gain medium is adjustable.

4 . The laser oscillator system according to claim 1 , wherein the imaging unit comprises one or more telescopes for imaging the intra-cavity laser beam, and wherein the one or more telescopes optionally contain one or more 4 f-telescopes.

5 . The laser oscillator system according to claim 4 , wherein an end minor of the resonator cavity is arranged in one of the imaging planes of the one or more telescopes.

6 . The laser oscillator system according to claim 1 , wherein the resonator cavity and optionally the imaging unit comprise one or more multipass-cells, and wherein the one or more multipass-cells optionally comprise one or more Herriott-type cells.

7 . The laser oscillator system according to claim 1 , wherein the Cr-doped II-VI gain medium comprises or consists of ZnS and/or ZnSe, and wherein the ZnS and/or the ZnSe optionally are polycrystalline.

8 . The laser oscillator system according to claim 1 , wherein the gain medium is oriented at a Brewster angle at the central wavelength of the intra-cavity laser beam or at a normal incidence angle of the intra-cavity laser beam.

9 . The laser oscillator system according to claim 1 , wherein the resonator cavity and the imaging unit are configured such that the laser oscillator system emits laser pulses at a repetition rate of 40 MHz or less.

10 . The laser oscillator system according to claim 1 , wherein the laser oscillator system is configured to emit the laser pulses having a pulse duration of 30 fs FWHM or less and/or a peak power of at least 0.75 MW and optionally of at least 1 MW.

11 . The laser oscillator system according to claim 1 , wherein the emitted laser pulses cover a spectral range from at least 2.0 μm to 2.8 μm.

12 . The laser oscillator system according to claim 1 , wherein the laser oscillator system is configured as a Kerr-lens mode-locked laser oscillator system.

13 . The laser oscillator system according to claim 12 , wherein the gain medium is configured to provide a functionality of a Kerr medium for Kerr-lens mode locking.

14 . The laser oscillator system according to claim 12 , further comprising a Kerr medium, wherein the Kerr medium is provided separately from the gain medium.

15 . The laser oscillator system according to claim 1 , wherein the Cr-doped II-VI gain medium is directly diode-pumped.

16 . A laser system, comprising:
the laser oscillator system according to claim 1 , wherein the laser oscillator system is configured to emit laser pulses having a peak power of at least 0.75 MW; a nonlinear optical element having a thickness of 1 mm or less;
wherein the laser system is configured to irradiate the nonlinear optical element with the laser pulses emitted by the laser oscillator system to spectrally broaden the laser pulses such that the spectrally broadened laser pulses span at least half an optical octave.

17 . The laser system according to claim 16 , wherein the laser system is configured to focus the laser pulses onto the nonlinear optical element.

18 . The laser system according to claim 16 , wherein the laser system is configured such that the spectrum of the laser pulses supports a pulse duration of 15 fs or less after propagating through the nonlinear optical element.

19 . The laser system according to claim 16 , wherein the nonlinear optical element comprises an anti-reflection coating at the surface facing the incident laser pulses.

20 . The laser system according to claim 16 , wherein the nonlinear optical element is arranged in a Brewster angle with respect to a direction of incidence of the laser pulses at a central wavelength of the laser pulses, and wherein the nonlinear optical element is formed of a birefringent crystal cut at an angle, such that a k-vector of the incident laser pulses is parallel to an optical axis of the birefringent crystal.

21 . The laser system according to claim 16 , wherein the nonlinear optical element comprises or consists of TiO 2 .

22 . The laser system according to claim 21 , wherein the nonlinear optical element comprises or consists of rutile TiO 2 .

23 . The laser system according to claim 16 , further comprising a second nonlinear optical element for spectral broadening in the mid-infrared spectral range, wherein the second nonlinear optical element optionally comprises or consists of ZnGeP 2 , and wherein the laser system is configured such that the laser pulses propagating through the second nonlinear optical element experience nonlinear frequency conversion.

24 . A method for generating light pulses having spectral components at a wavelength of at least 2 μm, the method comprising:
providing laser pulses emitted by a laser oscillator having a pulse duration of 30 fs FWHM or less, a peak power of at least 0.75 MW, and a central wavelength of 1.8 μm or longer; and
focusing the laser pulses onto a nonlinear optical element having a thickness of 1 mm or less and a nonlinear refractive index n 2 of at least 5·10 −19 m 2 /W at a wavelength of 2 μm.

25 . The method according to claim 24 , wherein the nonlinear optical element is a nonlinear optical element for nonlinear frequency conversion comprising or consisting of ZnGeP 2 .

26 . The method according to claim 24 , wherein the nonlinear optical element comprises or consists of TiO 2 and optionally of rutile TiO 2 .

27 . The method according to claim 26 , wherein the nonlinear optical element has a thickness being not more than ten times larger than a one-sided Rayleigh length of the laser pulses focused into the nonlinear optical element.

28 . The method according to claim 26 , further comprising focusing the laser pulses onto a second nonlinear optical element comprising or consisting of ZnGeP 2 , wherein the laser pulses propagating through the second nonlinear optical element experience nonlinear frequency conversion.

29 . The method according to claim 24 , wherein the laser oscillator comprises:
a resonator cavity configured to confine an intra-cavity laser beam; a Cr-doped II-VI gain medium arranged within the resonator cavity; and an imaging unit forming part of the resonator cavity, wherein the imaging unit is configured to decouple a spot size of the intra-cavity laser beam at the gain medium from an intra-cavity length of the resonator cavity, and wherein the resonator cavity and the imaging unit are configured such that the laser oscillator system emits laser pulses at a repetition rate of 50 MHz or less.

30 . A method for gener

Assignees

• Max Planck Gesellschaft
• Univ Muenchen Ludwig Maximilians

Inventors

• Mak Ka Fai
• Krausz Ferenc
• Steinleitner Philipp
• Lenke Nathalie

Classifications

• H01S3/09415 Primary

  the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping · CPC title

• H01S3/0057

  Temporal shaping, e.g. pulse compression, frequency chirping (soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108) · CPC title

• H01S3/08059

  Constructional details of the reflector, e.g. shape (mirrors in general G02B5/08; mountings for mirrors G02B7/18) · CPC title

• H01S5/142

  which comprises an additional resonator · CPC title

• H01S3/08 Primary

  Construction or shape of optical resonators or components thereof · CPC title