Multi-wavelength, ultrashort pulse generation and delivery, with applications in microscopy

Patent metadata

Field	Value
Publication number	US-9825419-B2
Application number	US-201615245082-A
Country	US
Kind code	B2
Filing date	Aug 23, 2016
Priority date	Feb 28, 2014
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

In one aspect, the present disclosure describes a fiber laser system for the generation and delivery of femtosecond (fs) pulses in multiple wavelength ranges. For improved versatility in multi-photon microscopy, an example of a dual wavelength fiber system based on Nd fiber source providing gain at 920 and 1060 nm is described. An example of a three-wavelength system is included providing outputs at 780 nm, 940 nm, and 1050 nm. The systems include dispersion compensation so that high quality fs pulses are provided for applications in microscopy, for example in multiphoton microscope (MPM) systems.

First claim

What is claimed is:

1. A laser system configured to provide ultrashort pulses at a plurality of output wavelengths, λ 1 . . . λ n , wherein n≧2, said laser system comprising:
at least one mode locked laser configured to generate ultrashort input pulses having one or more wavelengths;
dispersive optical components disposed downstream from said at least one mode locked laser; and
an optical delivery fiber configured such that at each of said wavelengths, λ 1 . . . λ n , net dispersion exhibited by said at least one mode locked laser, said dispersive optical components and said optical delivery fiber substantially compensates a net dispersion of an end use device disposed downstream from said laser system, said end use device configured to irradiate a sample with ultrashort pulses,
wherein said end use device is configured to deliver femtosecond pulses having a selected plurality of said output wavelengths λ 1 . . . λ n , to said sample, each of said femtosecond pulses substantially compensated for the net dispersion of said laser system and said end use device.

2. The laser system according to claim 1 , wherein said at least one mode locked laser comprises at least one mode locked fiber oscillator.

3. The laser system according to claim 2 , wherein said at least one mode locked fiber oscillator comprises one or more of an Nd fiber oscillator, a Yb fiber oscillator, an Er fiber oscillator, a Tm fiber oscillator, or a Ho fiber oscillator.

4. The laser system according to claim 2 , wherein said at least one mode locked fiber oscillator generates input pulses having one or more wavelengths of said plurality of output wavelengths, λ 1 . . . λ n .

5. The laser system according to claim 1 , further comprising an optical modulator receiving pulses at said plurality of wavelengths, said modulator configured to controllably select one or more pulses at said plurality of wavelengths and/or to control the output power at said wavelengths.

6. The laser system according to claim 5 , wherein said optical modulator comprises an acousto-optic modulator, an electro-optic modulator, or an integrated Mach Zehnder modulator.

7. The laser system according to claim 1 , further comprising a controller in communication with said end use device.

8. The laser system according to claim 1 , wherein said optical delivery fiber is configured with pre-selected dispersion at multiple wavelengths of said plurality of output wavelengths, λ 1 . . . λ n .

9. The laser system according to claim 1 , wherein n=2, and said wavelengths are approximately 920 nm and 1060 nm.

10. The laser system according to claim 1 , wherein n=3, and said wavelengths are approximately 920 nm, 1060 nm, and 1300 nm.

11. The laser system according to claim 1 , wherein n=3, and said wavelengths are approximately 780 nm, 940 nm and 1050 nm or approximately 780 nm, 950 nm and 1320 nm.

12. The laser system according to claim 1 , wherein said system comprises a Raman shifting fiber configured for Raman soliton propagation.

13. The laser system according to claim 12 , wherein said Raman shifting fiber shifts an input wavelength to one or more of the plurality of output wavelengths λ 1 . . . λ n .

14. The laser system according to claim 12 , wherein said Raman shifting fiber produces an output wavelength of about 2600 nm, and said system comprises a frequency doubler to generate 1300 nm optical pulses.

15. The laser system according to claim 1 , wherein said system comprises a frequency converter configured for upconverting a frequency of optical pulses.

16. The laser system according to claim 1 , wherein said system comprises a crystal for difference frequency generation (DFG), and an output from said DFG comprises one of more of the wavelengths λ 1 . . . λ n .

17. The laser system according to claim 1 , wherein said optical delivery fiber comprises a hollow core photonic crystal fiber (HC-PCF), a hollow core photonic bandgap fiber (HC-PBGF), or a Kagome fiber.

18. The laser system according to claim 1 , wherein said optical delivery fiber exhibits slightly anomalous dispersion at one or more output wavelengths, λ 1 . . . λ n .

19. The laser system according to claim 1 , wherein said ultrashort pulses irradiating said sample are nearly transform limited, and comprise pulse widths in the range from about 100 fs to about 1 ps with pulse pedestal substantially below 10% of a peak value of the ultrashort pulses.

20. The laser system according to claim 1 , wherein said dispersive components disposed downstream from said at least one mode locked laser comprise specialty fiber arranged to pre-chirp an input signal and vary a pulse width of said input signal via normal or anomalous dispersion.

21. The laser system according to claim 1 , wherein λ 1 . . . λ n comprises a wavelength at or near 920 nm.

22. The laser system according to claim 1 , said wavelength comprising, as λ 1 , the 900 to 950 nm wavelength range and, as λ 2 , the 1030 to 1080 nm wavelength range, wherein said system configured with a single Nd power amplifier simultaneously amplifying optical pulses having respective wavelengths in each of the two wavelength ranges λ 1 and λ 2 .

23. The laser system according to claim 1 , further comprising: an optical parametric amplifier (OPA) disposed between said at least one mode locked laser and said optical delivery fiber, wherein said OPA generates a plurality of OPA output wavelengths, n>2, for use in said end use device, and wherein said optical delivery fiber is configured with dispersion at each of said OPA wavelengths such that compressed optical pulses having pulse widths less than about 200 fs are provided from said end use device to irradiate said sample.

24. An end use device utilizing ultrashort pulses to irradiate a sample, the end use device comprising:
the laser system according to claim 1 ; and
delivery and focusing optics having predetermined net dispersion at each of a plurality of wavelengths, λ 1 . . . λ n , wherein n≧2,
wherein the net dispersion in each of said laser system and said end use device at each of said wavelengths λ 1 . . . λ n is sufficiently compensated to result in nearly transform limited ultrashort pulses having pulse widths in the range from about 100 fs to about 1 ps.

25. A laser system configured to generate ultrashort pulses to irradiate a sample, comprising:
a mode locked laser configured to generate input pulses;
a highly nonlinear fiber configured to generate a frequency broadened spectrum downstream of said mode locked laser, said broadened spectrum overlapping at least partially with a signal wavelength range Δλ,
dispersive optical components disposed downstream from said mode locked laser;
an optical parametric amplifier (OPA) disposed downstream from said mode locked laser, said OPA configured to amplify optical pulses with a corresponding pulse spectrum within the wavelength range Δλ; and
an optical delivery fiber configured such that within said wavelength range Δλ, the net dispersion exhibited by said mode locked laser, said dispersive optical components, said OPA, and said optical delivery fiber substantially compensates a net dispersion of an end use apparatus disposed downstream from said laser system, said end use apparatus configured to irradiate a sample with femtosecond pulses generated with said OPA.

Assignees

• Imra America Inc

Inventors

• Hori Takashi
• Fermann Martin E

Classifications

• H01S3/1106

  Mode locking · CPC title

• H01S3/0085

  Modulating the output, i.e. the laser beam is modulated outside the laser cavity · CPC title

• H01S3/005

  Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping (shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B) · CPC title

• H01S3/1618

  ytterbium · CPC title

• H01S2301/085

  solitons · CPC title