Pulse configurable fiber laser unit

Patent metadata

Field	Value
Publication number	US-11817670-B2
Application number	US-201916561968-A
Country	US
Kind code	B2
Filing date	Sep 5, 2019
Priority date	Sep 5, 2018
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

A pulse configurable laser unit is an environmentally stable, mechanically robust, and maintenance-free ultrafast laser source for low-energy industrial, medical and analytical applications. The key features of the laser unit are a reliable, self-starting fiber oscillator and an integrated programmable pulse shaper. The combination of these components allows taking full advantage of the laser's broad bandwidth ultrashort pulse duration and arbitrary waveform generation via spectral phase manipulation. The source can routinely deliver near-TL, sub-60 fs pulses with megawatt-level peak power. The output pulse dispersion can be tuned to pre-compensate phase distortions down the line as well as to optimize the pulse profile for a specific application.

First claim

The invention claimed is:

1. A pulse configurable laser unit (PCLU) outputting uniform ultrashort pulses, comprising:
a fiber pulse generator operating in a plurality of operational regimes to output a train of coherent uniform amplified giant chirped broadband pulses along a light path, the fiber pulse generator being a self-starting passively mode-locked fiber seed which has two identical groups of optical elements defining a ring resonator;
a two-stage compressor including
a static compressor, which is configured to compensate for a linear chirp component of each giant chirped broadband pulse, and
a pulse shaper which is provided with a programmable spatial light modulator (SLM) to correct for a non-linear chirp component of the giant chirped broadband pulse, wherein the two-stage compressor outputs a train of transform limited (TL) ultrashort coherent pulses in each of the operational regimes of the fiber pulse laser generator; and

at least one or more computers executing a software for selectively retrieving a phase mask corresponding to a given operational regime from a library of phase masks, which is stored in a memory of the CPU, and operating the pulse shaper to apply the retrieved mask across to the programmable spatial light modulator (SLM) of the pulse shaper so as to compensate for the nonlinear chirp component of each giant chirped pulse.

2. The PCLU of claim 1 , wherein the computer executes the software for retrieving an amplitude mask from a library of amplitude masks, which are stored in the memory of the CPU, and apply the retrieved amplitude mask across a programmable spatial light modulator (SIM) of the pulse shaper to suppress parasitic intensity peaks present in a spectrum of the TL pulse.

3. The PCLU of claim 1 , wherein the computer executes the software for retrieving a phase mask from the library of phase masks and applying the retrieved phase mask across the SLM of the pulse shaper to reshape the TL pulse into a pulse differing from the TL pulse, but having a desired shape for the given operational regime of the pulse generator.

4. The PCLU of claim 3 , wherein the computer executes the software for retrieving an amplitude mask from a library of amplitude masks phase masks and applying the retrieved amplitude mask across the pulse shaper to refine the desired shape of the pulse different from the TL pulse.

5. The PCLU of claim 1 , wherein the pulse shaper is configured with is a spatial light modulator (SLM) including a liquid crystal spatial light modulator (LC SLM), liquid crystal phase (LCOS), an acousto-optical modulator (AOM) or an acousto-optical programmable dispersive filter (AOPDF).

6. The PCLU of claim 1 , wherein the software executed by the computer measures and corrects phases of spectral pulse components in accordance with a multiphoton intrapulse interference phase scan (MIIPS) algorithm.

7. The PCLU of claim 1 , wherein the optical elements of each groups include an Yb doped active fibers, fiber coil and narrow line spatial filter, the spatial filters of respective groups being configured to have respective spectrums overlapping one another, the elements being optically coupled to one another by a plurality of passive fibers.

8. The PCLU of claim 7 , wherein the pulse generator further includes a fiber booster, the fiber booster being configured with the elements defining the ring resonator but coupled to one another such that the booster has a linear geometry, the active and passive fibers of the booster having respective substantially uniformly dimensioned cores larger than substantially uniformly dimensioned cores of respective elements of the ring resonator.

9. The PCLU of claim 1 , wherein the pulse shaper is one-dimensional or two dimensional.

10. The PCLU of claim 4 , wherein the phase and amplitude masks applied to the TL pulse to provide the pulse with the desired shape which includes regular and irregular shapes in time and frequency domains.

11. The PCLU of claim 1 , wherein the self-starting passively mode-locked fiber seed outputs a train of coherent broadband chirped coherent pulses at up to 20 MHz pulse repetition rate, each pulse having an energy of up to 50 nJ and a full spectral bandwidth of up to 100 nm.

12. The PCLUm of claim 8 , wherein the pulse generator having the fiber booster yields a train of coherent broadband chirped coherent pulses at up to 20 MHz pulse repetition rate, each pulse having a full spectral bandwidth of up to 100 nm and a pulse energy of up to 500 nJ.

13. A method of generating ultrafast pulses, comprising:
(a) operating a self-starting passively mode-locked fiber seed in a plurality of operational regimes, thereby generating a train of pulses, wherein each pulses acquires a giant chirp through a nonlinear evolution of the pulse in the laser source, wherein the fiber seed has two identical groups of optical elements defining a ring resonator;
(b) compressing the chirped pulses to respective transform-limited (TL) pulses in each of the operational regimes by:
correcting the linear component of the giant chirp, and
correcting the nonlinear component of the giant chirp by applying a spectral phase mask to the chirped pulse upon retrieving the applied phase mask from a computer library, wherein multiple phase masks are generated to correspond to respective operational regimes;

(c) shaping the TL pulses corresponding to respective operational regimes by applying spectral phase masks or spectral phased masks and amplitude masks retrieved from the computer library, thereby generating desired pulse shapes of respective TL pulses.

14. The method of claim 13 , wherein the step (c) further comprises applying amplitude masks stored in the library and corresponding to respective operational regimes, thereby suppressing parasitic low intensity pulses in an intensity profile of each TL pulse.

15. The method of claim 13 further comprising storing source parameters corresponding to respective operating regimes in the library of a computer memory.

Assignees

• Ipg Photonics Corp

Inventors

• Bordenyuk Andrey
• Pestov Dmitry
• Lozovoy Vadim
• Samartsev Igor

Classifications

• H01S3/06725 Primary

  Fibre characterized by a specific dispersion, e.g. for pulse shaping in soliton lasers or for dispersion compensating [DCF] · CPC title

• G02F1/00

  Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics · CPC title

• G02F1/01

  for the control of the intensity, phase, polarisation or colour  (G02F1/29, G02F1/35 take precedence) · CPC title

• G02F1/11

  based on acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves (acousto-optical deflection G02F1/33) · CPC title

• G02F1/113

  Circuit or control arrangements · CPC title