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DE-102024133221-A1 - Device, laser arrangement and method for spectral broadening of a pulsed laser beam

DE102024133221A1DE 102024133221 A1DE102024133221 A1DE 102024133221A1DE-102024133221-A1

Abstract

The invention relates to a device (10) for spectral broadening of a pulsed laser beam (12) by means of self-phase modulation with features of claim 1 and a laser arrangement (32) for spectral broadening of a pulsed laser beam (12) by means of self-phase modulation with features of the dependent claim.

Inventors

  • Jonas Manz
  • Sandro Klingebiel
  • Gaia Barbiero
  • Ronak Narendra Shah
  • Dominik Ertel
  • Haochuan Wang
  • Aiswarya Surendran
  • Michael Rampp
  • Thomas Metzger

Assignees

  • TRUMPF SCIENTIFIC LASERS GMBH + CO. KG

Dates

Publication Date
20260513
Application Date
20241113

Claims (14)

  1. Device (10) for spectral broadening of a pulsed laser beam (12) by means of self-phase modulation comprising: - a chamber (16) filled with a gas (14) or gas mixture, wherein the chamber (16) has a first transmission region (18) and a second transmission region (20) for the passage of the laser beam (12) into and/or out of the chamber (16), - at least one first mirror (24), - at least one second mirror (26), wherein the first mirror (24) and the second mirror (26) are arranged outside the chamber (16) and configured to reflect the laser beam (12) multiple times, in particular more than 4 times, preferably more than 10 times, between the first mirror (24) and the second mirror (26) and through the chamber (16), wherein the gas (14) causes a spectral broadening of the laser beam (12).
  2. Device (10) according to Claim 1 , characterized in that the device (10) is designed as a multipass cell, in particular a Herriott cell or Bow-Tie cavity.
  3. Device (10) according to Claim 1 or 2 , characterized in that the first transmission region (18) and/or the second transmission region (20) comprises or is formed from a nonlinear optical solid medium (22), wherein the nonlinear optical solid medium (22) causes a spectral broadening of the laser beam (12).
  4. Device (10) according to Claim 1 or 2 , characterized in that the gas (14) in the chamber (16) is a noble gas, in particular argon, helium, krypton or xenon, or that the gas mixture in the chamber (16) comprises a noble gas, in particular argon or helium.
  5. Device (10) according to one of the preceding claims, characterized in that the first mirror (24) and the second mirror (26) are arranged such that the laser beam (12) reflected between them forms a focus.
  6. Device (10) according to one of the preceding claims, characterized in that the first transmission area (18) and/or the second transmission area (20) each comprise a window (28) or are each designed as a window (28).
  7. Device (10) according to the preceding claim, characterized in that the window (28) is made of quartz glass or sapphire glass.
  8. Device (10) according to one of the two preceding claims, characterized in that the window (28) has an anti-reflective coating.
  9. Device (10) according to one of the preceding claims, characterized in that the first mirror (24) and/or second mirror (26) are each arranged at a distance from the chamber (16), in particular wherein air is arranged between the first mirror (24) and the chamber (16) and/or between the second mirror (26) and the chamber (16).
  10. Device (10) according to one of the preceding claims, characterized in that the chamber (16) is designed to be evacuated.
  11. Device (10) according to one of the preceding claims, characterized in that the chamber (16) is arranged such that a gas pressure within the chamber (16) can be adjusted.
  12. Device (10) according to one of the preceding claims, characterized in that the chamber (16) has a base body (30), wherein the base body (30) is designed as a tube, in particular with a round, preferably circular, cross-section, and in particular wherein the base body (30) is made of metal or glass.
  13. Laser arrangement (32) for spectral broadening of a pulsed laser beam (12) by means of self-phase modulation comprising: - a laser source (34) for generating the laser beam (12), - a device (10) according to one of the preceding claims, - an input optic (36), in particular a mode-matching telescope, for coupling the laser beam (12) into the device (10), - an output optic (38), in particular a mirror, for coupling the laser beam (12) out of the device (10).
  14. Laser arrangement (32) according to the preceding claim, characterized in that the laser arrangement (32) comprises a compressor (40), in particular a chirped mirror compressor or a grating compressor, for compression of the laser beam (12).

Description

The invention relates to a device for spectral broadening of a pulsed laser beam by means of self-phase modulation with features of claim 1 and a laser arrangement for spectral broadening of a pulsed laser beam by means of self-phase modulation with features of claim 12. Self-phase modulation (SPM) of a laser beam is a nonlinear optical effect based on the intensity dependence of the refractive index in materials. It occurs when an intense laser beam is passed through a nonlinear medium and undergoes a frequency-dependent phase shift, leading to the generation of new frequency components within the laser beam. This effect is of central importance for applications in the generation of ultrashort laser pulses via spectral broadening. DE 10 2020 204 808 A1 Disclosure reveals a device for spectral broadening of laser pulses by means of several mirror elements between which a laser beam is reflected back and forth. The laser beam passes through a disk-shaped nonlinear optical solid medium to generate a nonlinear phase through self-phase modulation. The mirror elements are arranged in a gas-filled chamber. The object of the present invention is to provide a device, a laser system and a method for spectral broadening of a pulsed laser beam, in which the susceptibility to interference, the complexity, the costs and the required passes or passages of the laser beam can be reduced. The above problem is solved by a device for spectral broadening of a pulsed laser beam by means of self-phase modulation with the features of claim 1. The spectral broadening can be performed in the pico- or femtosecond regime. The device comprises a chamber filled with a gas or gas mixture. The chamber has a first transmission region and a second transmission region for the passage of the laser beam into and/or out of the chamber. The device comprises at least one first mirror and at least one second mirror. The first and second mirrors are arranged outside the chamber and configured to reflect the laser beam multiple times, in particular more than four times, preferably more than ten times, between the first and second mirrors and through the chamber. The gas causes a spectral broadening of the laser beam. Compared to a conventional gas-based multipass cell, the arrangement of mirrors within the vacuum chamber is unnecessary. This eliminates the need for complex mechanics required to prevent mirror misalignment during evacuation and gas filling of the chamber. The chamber size (especially length and diameter) can be reduced because the first and second mirrors are located outside the chamber. This significantly reduces the required gas volume. Adjusting and, in particular, verifying the laser beam size (or diameter) on the mirrors is simplified, as the first and second mirrors are directly accessible. According to a further development of the device, it can be configured as a multipass cell. The device can be configured as a Herriott cell or a Bow-Tie cavity. It is also conceivable that the device could have a concave-convex structure or be configured as another folded cell. In particular, all optics can be arranged outside the chamber. This allows the device to be implemented using simple means. According to a further development of the device, the first transmission area and/or the second transmission area can comprise or be formed from a nonlinear optical solid medium. This allows for the exploitation of gas-based and solid-state medium-based nonlinearities using simple means. The susceptibility to interference, the complexity, the costs, and the number of laser beam passes required for spectral broadening can be reduced. Due to the reduction in passes, the mirrors can be made smaller and more cost-effective. Compared to a conventional solid-state-based multipass cell, significantly fewer passes or cycles are required due to the higher usable nonlinearity (B-integral) resulting from the additional use of the gas or gas mixture as a nonlinear medium. This allows the first and/or second mirror to be smaller, reducing material costs, losses, and the size of the device. Due to the additional nonlinearity provided by the Higher compression factors can be achieved with gas or gas mixtures (in the conventional solid-state-based multipass cell, two diffusion stages are often necessary). According to a further development of the device, the gas in the chamber can be a noble gas, in particular argon, helium, krypton, or xenon. Alternatively, the gas mixture in the chamber can comprise a noble gas, in particular argon, helium, krypton, or xenon. This allows the device to be further optimized using simple means. According to a further development of the device, the first mirror and the second mirror can be arranged such that the laser beam reflected between them forms a focus. It is also conceivable that the first mirror and the second mirror can be arranged such that the laser beam reflected between them forms a caustic. This allows for the impl