# US 2013/0278997 A1 · 2 micron Femtosecond Fiber Laser

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- Number: US 2013/0278997 A1
- Document ID: US20130278997A1
- Status: Published application
- Kind: A1
- Application number: 13/452,817
- Filed: 2012-04-20
- Published: 2013-10-24
- Earliest claimed: 2012-04-20
- Assignees: PolarOnyx, Inc.
- Inventors: Jian Liu; Peng Wan; Lihmei Yang
- Web page: https://patentgrep.com/patent/US20130278997A1

## CPC

- H01S 3/067: Fibre lasers
- H01S 3/1118: Semiconductor saturable absorbers, e.g. semiconductor saturable absorber mirrors [SESAMs]; Solid-state saturable absorbers, e.g. carbon nanotube [CNT] based
- H01S 3/161: {holmium}
- H01S 3/1616: {thulium}
- H01S 3/06725: {Fibre characterized by a specific dispersion, e.g. for pulse shaping in soliton lasers or for dispersion compensating [DCF]}
- H01S 3/06754: {Fibre amplifiers (H01S3/06708 takes precedence)}
- H01S 3/083: Ring lasers {(fibre ring lasers H01S3/06791)}
- H01S 3/1112: Passive mode locking
- H01S 3/1698: {rare earth}
- 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

## Abstract

Methods and systems for generating femtosecond fiber laser pulses are disclose, including generating a signal laser pulse from a seed laser oscillator; using a first amplifier stage comprising an input and an output, wherein the signal laser pulse is coupled into the input of the first stage amplifier and the output of the first amplifier stage emits an amplified and stretched signal laser pulse; using an amplifier chain comprising an input and an output, wherein the amplified and stretched signal laser pulse from the output of the first amplifier stage is coupled into the input of the amplifier chain and the output of the amplifier chain emits a further amplified, stretched signal laser pulse. Other embodiments are described and claimed.

## Claims

### Claim 1

A fiber laser comprising:
a seed laser oscillator comprising an output;
a first amplifier stage comprising an input and an output, wherein the output of the seed laser oscillator is coupled to the input of the first stage amplifier; and
an amplifier chain comprising an input and an output, wherein the input of the amplifier chain is coupled to the output of the first amplifier stage and the output of the amplifier chain is configured to emit an amplified laser pulse.

### Claim 2 (depends on 1)

The fiber laser of claim 1, wherein the amplified laser pulse has an energy ranging from 0.1 μJ to 10 mJ.

### Claim 3 (depends on 1)

The fiber laser of claim 1, wherein the amplified laser pulse has a wavelength ranging from 1850 nm to 2100 nm.

### Claim 4 (depends on 1)

The fiber laser of claim 1, wherein the fiber laser further comprises a compressor comprising an input and an output, wherein the input of the compressor is coupled to the output of the amplifier chain and the compressor is configured for anomalous dispersion of the amplified laser pulse to emit a femtosecond laser pulse from the output of the compressor.

### Claim 5 (depends on 1)

The fiber laser of claim 1, wherein the fiber laser further comprises a compressor comprising an input and an output, wherein the input of the compressor is coupled to the output of the amplifier chain and the compressor is configured for normal dispersion of the amplified laser pulse to emit a femtosecond laser pulse from the output of the compressor.

### Claim 6 (depends on 1)

The fiber laser of claim 1, wherein the seed laser oscillator comprises a linear cavity, wherein the linear cavity comprises:
a fiber reflector;
a dispersion compensating fiber comprising an input and an output, wherein the fiber reflector is coupled to the input of the dispersion compensating fiber;
an output coupler comprising a first port, a second port, and an output, wherein the output of the dispersion compensating fiber is coupled to the first port of the output coupler;
one or more pump diodes;
a signal/pump combiner comprising an input and an output, wherein the one or more pump diodes and the second port of the output coupler are coupled to the input of the signal/pump combiner;
a gain fiber comprising a doped gain medium, an input, and an output, wherein the output of the signal/pump combiner is coupled to the input of the gain fiber;
a SESAM coupled to the output of the gain fiber;
a polarization maintaining isolator comprising an input and an output, wherein the output of the signal/pump combiner is coupled to the input of the polarization maintaining isolator and the output of the polarization maintaining isolator is configured to emit a signal laser pulse.

### Claim 7 (depends on 6)

The fiber laser of claim 6, wherein the one or more pump diodes and the signal/pump combiner are multimode and the linear cavity further comprises a pump stripper coupled between the gain fiber and the SESAM.

### Claim 8 (depends on 6)

The fiber laser of claim 6, wherein the signal laser pulse has a pulse repetition rate ranging from 100 kHz to 1,000 MHz.

### Claim 9 (depends on 6)

The fiber laser of claim 6, wherein the one or more pump diodes have a wavelength ranging from 790 nm to 796 nm.

### Claim 10 (depends on 6)

The fiber laser of claim 6, wherein the one or more pump diodes have a wavelength ranging from 1200 nm to 1220 nm.

### Claim 11 (depends on 6)

The fiber laser of claim 6, wherein the one or more pump diodes have a wavelength ranging from 1570 nm to 1620 nm.

### Claim 12 (depends on 6)

The fiber laser of claim 6, wherein the doped gain medium is at least one of: Thulium, Holmium, and Thulium/Holmium.

### Claim 13 (depends on 6)

The fiber laser of claim 6, wherein the gain fiber comprises a single cladding or a double cladding.

### Claim 14 (depends on 6)

The fiber laser of claim 6, wherein the gain fiber comprises a core size ranging from 5 μm to 200 μm.

### Claim 15 (depends on 6)

The fiber laser of claim 6, wherein the gain fiber comprises a numerical aperture ranging from 0.02 to 0.25.

### Claim 16 (depends on 1)

The fiber laser of claim 1, wherein the seed laser oscillator comprises a ring cavity, wherein the ring cavity comprises:
one or more pump diodes;
a signal/pump combiner comprising an input and an output, wherein the one or more pump diodes are coupled to the input of the signal/pump combiner;
a gain fiber comprising a doped gain medium, an input, and an output, wherein the output of the signal/pump combiner is coupled to the input of the gain fiber;
an output coupler comprising a first port, a second port, and an output, wherein the output of the gain fiber is coupled to the first port of the output coupler and the output of the output coupler is configured to emit a signal laser pulse;
a first in line polarization controller comprising an input and an output, wherein the second port of the output coupler is coupled to the input of the first in line polarization controller;
an in line polarization isolator comprising an input and an output, wherein the output of the first in line polarization controller is coupled to the input of the in line polarization isolator;
a second in line polarization controller comprising an input and an output, wherein the output of the in line polarization isolator is coupled to the input of the second in line polarization controller; and
a dispersion compensating fiber comprising an input and an output, wherein the output of the second in line polarization controller is coupled to the input of the dispersion compensating fiber and the input of the signal/pump combiner is coupled to the output of the dispersion compensating fiber.

### Claim 17 (depends on 16)

The fiber laser of claim 16, wherein the one or more pump diodes and the signal/pump combiner are multimode and the ring cavity further comprises a pump stripper coupled between the gain fiber and the output coupler.

### Claim 18 (depends on 16)

The fiber laser of claim 16, wherein the one or more pump diodes have a wavelength ranging from 790 nm to 796 nm.

### Claim 19 (depends on 16)

The fiber laser of claim 16, wherein the one or more pump diodes have a wavelength ranging from 1200 nm to 1220 nm.

### Claim 20 (depends on 16)

The fiber laser of claim 16, wherein the one or more pump diodes have a wavelength ranging from 1570 nm to 1620 nm.

### Claim 21 (depends on 16)

The fiber laser of claim 16, wherein the doped gain medium is at least one of: Thulium, Holmium, and Thulium/Holmium.

### Claim 22 (depends on 16)

The fiber laser of claim 16, wherein the gain fiber comprises a single cladding or a double cladding.

### Claim 23 (depends on 16)

The fiber laser of claim 16, wherein the gain fiber comprises a core size ranging from 5 μm to 200 μm.

### Claim 24 (depends on 16)

The fiber laser of claim 16, wherein the gain fiber comprises a numerical aperture ranging from 0.02 to 0.25.

### Claim 25 (depends on 1)

The fiber laser of claim 1, wherein the first amplifier stage further comprises:
a spool of dispersion fiber comprising an input and an output, wherein the output of the seed laser oscillator is coupled to the input of the spool of dispersion fiber;
one or more pump diodes;
a signal/pump combiner comprising an input and an output, wherein the one or more pump diodes and the output of the spool of dispersion fiber are coupled to the input of the signal/pump combiner;
a gain fiber comprising a doped gain medium, an input, and an output, wherein the output of the signal/pump combiner is coupled to the input of the gain fiber;
a polarization maintaining isolator comprising an input and an output, wherein the output of the gain fiber is coupled to the input of the polarization maintaining isolator and the output of the polarization maintaining isolator is configured to emit a stretched and amplified laser pulse.

### Claim 26 (depends on 25)

The fiber laser of claim 25, wherein the one or more pump diodes and the signal/pump combiner are multimode and the first amplifier stage further comprises a pump stripper coupled between the gain fiber and the polarization maintaining isolator.

### Claim 27 (depends on 25)

The fiber laser of claim 25, wherein the spool of dispersion fiber comprises normal dispersion fiber or anomalous dispersion fiber.

### Claim 28 (depends on 25)

The fiber laser of claim 25, wherein the one or more pump diodes have a wavelength ranging from 790 nm to 796 nm.

### Claim 29 (depends on 25)

The fiber laser of claim 25, wherein the one or more pump diodes have a wavelength ranging from 1200 nm to 1220 nm.

### Claim 30 (depends on 25)

The fiber laser of claim 25, wherein the one or more pump diodes have a wavelength ranging from 1570 nm to 1620 nm.

### Claim 31 (depends on 25)

The fiber laser of claim 25, wherein the doped gain medium is at least one of: Thulium, Holmium, and Thulium/Holmium.

### Claim 32 (depends on 25)

The fiber laser of claim 25, wherein the gain fiber comprises a single cladding or a double cladding.

### Claim 33 (depends on 25)

The fiber laser of claim 25, wherein the gain fiber comprises a core size ranging from 5 μm to 200 μm.

### Claim 34 (depends on 25)

The fiber laser of claim 25, wherein the gain fiber comprises a numerical aperture ranging from 0.02 to 0.25.

### Claim 35 (depends on 1)

The fiber laser of claim 1, wherein the amplifier chain further comprises:
one or more amplifier units comprising:
one or more pump diodes;
a signal/pump combiner comprising an input and an output, wherein the one or more pump diodes and the output of the first amplifier stage are coupled to the input of the signal/pump combiner;
a gain fiber comprising a doped gain medium, an input, and an output, wherein the output of the signal/pump combiner is coupled to the input of the gain fiber;
a polarization maintaining isolator comprising an input and an output, wherein the output of the gain fiber is coupled to the input of the polarization maintaining isolator and the output of the polarization maintaining isolator is configured to emit the amplified laser pulse.

### Claim 36 (depends on 35)

The fiber laser of claim 35, wherein the one or more pump diodes and the signal/pump combiner are multimode and the one or more amplifier units further comprises a pump stripper coupled between the gain fiber and the polarization maintaining isolator.

### Claim 37 (depends on 35)

The fiber laser of claim 35, wherein the one or more pump diodes have a wavelength ranging from 790 nm to 796 nm.

### Claim 38 (depends on 35)

The fiber laser of claim 35, wherein the one or more pump diodes have a wavelength ranging from 1200 nm to 1220 nm.

### Claim 39 (depends on 35)

The fiber laser of claim 35, wherein the one or more pump diodes have a wavelength ranging from 1570 nm to 1620 nm.

### Claim 40 (depends on 35)

The fiber laser of claim 35, wherein the doped gain medium is at least one of: Thulium, Holmium, and Thulium/Holmium.

### Claim 41 (depends on 35)

The fiber laser of claim 35, wherein the gain fiber comprises a single cladding or a double cladding.

### Claim 42 (depends on 35)

The fiber laser of claim 35, wherein the gain fiber comprises a core size ranging from 5 μm to 200 μm.

### Claim 43 (depends on 35)

The fiber laser of claim 35, wherein the gain fiber comprises a numerical aperture ranging from 0.02 to 0.25.

### Claim 44

A method for generating femtosecond fiber laser pulses, the method comprising:
generating a signal laser pulse from a seed laser oscillator;
using a first amplifier stage comprising an input and an output, wherein the signal laser pulse is coupled into the input of the first stage amplifier and the output of the first amplifier stage emits an amplified and stretched signal laser pulse;
using an amplifier chain comprising an input and an output, wherein the amplified and stretched signal laser pulse from the output of the first amplifier stage is coupled into the input of the amplifier chain and the output of the amplifier chain emits a further amplified, stretched signal laser pulse.

### Claim 45 (depends on 44)

The method of claim 44, wherein the further amplified, stretched signal laser pulse has an energy ranging from 0.1 μJ to 10 mJ.

### Claim 46 (depends on 44)

The method of claim 44, wherein the further amplified, stretched signal laser pulse has a wavelength ranging from 1850 nm to 2100 nm.

### Claim 47 (depends on 44)

The method of claim 44, wherein the method further comprises:
using a compressor comprising an input and an output, wherein the input of the compressor is coupled to the output of the amplifier chain and the compressor is configured for anomalous dispersion of the further amplified, stretched signal laser pulse to emit a femtosecond laser pulse from the output of the compressor.

### Claim 48 (depends on 44)

The method of claim 44, wherein the method further comprises:
using a compressor comprising an input and an output, wherein the input of the compressor is coupled to the output of the amplifier chain and the compressor is configured for normal dispersion of the further amplified, stretched signal laser pulse to emit a femtosecond laser pulse from the output of the compressor.

### Claim 49 (depends on 44)

The method of claim 44, wherein the seed laser oscillator comprises a linear cavity, wherein the linear cavity comprises:
a fiber reflector;
a dispersion compensating fiber comprising an input and an output, wherein the fiber reflector is coupled to the input of the dispersion compensating fiber;
an output coupler comprising a first port, a second port, and an output, wherein the output of the dispersion compensating fiber is coupled to the first port of the output coupler;
one or more pump diodes;
a signal/pump combiner comprising an input and an output, wherein the one or more pump diodes and the second port of the output coupler are coupled to the input of the signal/pump combiner;
a gain fiber comprising a doped gain medium, an input, and an output, wherein the output of the signal/pump combiner is coupled to the input of the gain fiber;
a SESAM coupled to the output of the gain fiber;
a polarization maintaining isolator comprising an input and an output, wherein the output of the signal/pump combiner is coupled to the input of the polarization maintaining isolator and the output of the polarization maintaining isolator is configured to emit the signal laser pulse.

### Claim 50 (depends on 49)

The method of claim 49, wherein the one or more pump diodes and the signal/pump combiner are multimode and the linear cavity further comprises a pump stripper coupled between the gain fiber and the SESAM.

### Claim 51 (depends on 49)

The method of claim 49, wherein the signal laser pulse has a pulse repetition rate ranging from 100 kHz to 1,000 MHz.

### Claim 52 (depends on 49)

The method of claim 49, wherein the one or more pump diodes have a wavelength ranging from 790 nm to 796 nm.

### Claim 53 (depends on 49)

The method of claim 49, wherein the one or more pump diodes have a wavelength ranging from 1200 nm to 1220 nm.

### Claim 54 (depends on 49)

The method of claim 49, wherein the one or more pump diodes have a wavelength ranging from 1570 nm to 1620 nm.

### Claim 55 (depends on 49)

The method of claim 49, wherein the doped gain medium is at least one of: Thulium, Holmium, and Thulium/Holmium.

### Claim 56 (depends on 49)

The method of claim 49, wherein the gain fiber comprises a single cladding or a double cladding.

### Claim 57 (depends on 49)

The method of claim 49, wherein the gain fiber comprises a core size ranging from 5 μm to 200 μm.

### Claim 58 (depends on 49)

The method of claim 49, wherein the gain fiber comprises a numerical aperture ranging from 0.02 to 0.25.

### Claim 59 (depends on 44)

The method of claim 44, wherein the seed laser oscillator comprises a ring cavity, wherein the ring cavity comprises:
one or more pump diodes;
a signal/pump combiner comprising an input and an output, wherein the one or more pump diodes are coupled to the input of the signal/pump combiner;
a gain fiber comprising a doped gain medium, an input, and an output, wherein the output of the signal/pump combiner is coupled to the input of the gain fiber;
an output coupler comprising a first port, a second port, and an output, wherein the output of the gain fiber is coupled to the first port of the output coupler and the output of the output coupler is configured to emit the signal laser pulse;
a first in line polarization controller comprising an input and an output, wherein the second port of the output coupler is coupled to the input of the first in line polarization controller;
an in line polarization isolator comprising an input and an output, wherein the output of the first in line polarization controller is coupled to the input of the in line polarization isolator;
a second in line polarization controller comprising an input and an output, wherein the output of the in line polarization isolator is coupled to the input of the second in line polarization controller; and
a dispersion compensating fiber comprising an input and an output, wherein the output of the second in line polarization controller is coupled to the input of the dispersion compensating fiber and the input of the signal/pump combiner is coupled to the output of the dispersion compensating fiber.

### Claim 60 (depends on 59)

The method of claim 59, wherein the one or more pump diodes and the signal/pump combiner are multimode and the ring cavity further comprises a pump stripper coupled between the gain fiber and the output coupler.

### Claim 61 (depends on 59)

The method of claim 59, wherein the one or more pump diodes have a wavelength ranging from 790 nm to 796 nm.

### Claim 62 (depends on 59)

The method of claim 59, wherein the one or more pump diodes have a wavelength ranging from 1200 nm to 1220 nm.

### Claim 63 (depends on 59)

The method of claim 59, wherein the one or more pump diodes have a wavelength ranging from 1570 nm to 1620 nm.

### Claim 64 (depends on 59)

The method of claim 59, wherein the doped gain medium is at least one of: Thulium, Holmium, and Thulium/Holmium.

### Claim 65 (depends on 59)

The method of claim 59, wherein the gain fiber comprises a single cladding or a double cladding.

### Claim 66 (depends on 59)

The method of claim 59, wherein the gain fiber comprises a core size ranging from 5 μm to 200 μm.

### Claim 67 (depends on 59)

The method of claim 59, wherein the gain fiber comprises a numerical aperture ranging from 0.02 to 0.25.

### Claim 68 (depends on 44)

The method of claim 44, wherein the first amplifier stage further comprises:
a spool of dispersion fiber comprising an input and an output, wherein the signal laser pulse is coupled to the input of the spool of dispersion fiber;
one or more pump diodes;
a signal/pump combiner comprising an input and an output, wherein the one or more pump diodes and the output of the spool of dispersion fiber are coupled to the input of the signal/pump combiner;
a gain fiber comprising a doped gain medium, an input, and an output, wherein the output of the signal/pump combiner is coupled to the input of the gain fiber;
a polarization maintaining isolator comprising an input and an output, wherein the output of the gain fiber is coupled to the input of the polarization maintaining isolator and the output of the polarization maintaining isolator is configured to emit the amplified and stretched signal laser pulse.

### Claim 69 (depends on 68)

The method of claim 68, wherein the one or more pump diodes and the signal/pump combiner are multimode and the first amplifier stage further comprises a pump stripper coupled between the gain fiber and the polarization maintaining isolator.

### Claim 70 (depends on 68)

The method of claim 68, wherein the spool of dispersion fiber comprises normal dispersion fiber or anomalous dispersion fiber.

### Claim 71 (depends on 68)

The method of claim 68, wherein the one or more pump diodes have a wavelength ranging from 790 nm to 796 nm.

### Claim 72 (depends on 68)

The method of claim 68, wherein the one or more pump diodes have a wavelength ranging from 1200 nm to 1220 nm.

### Claim 73 (depends on 68)

The method of claim 68, wherein the one or more pump diodes have a wavelength ranging from 1570 nm to 1620 nm.

### Claim 74 (depends on 68)

The method of claim 68, wherein the doped gain medium is at least one of: Thulium, Holmium, and Thulium/Holmium.

### Claim 75 (depends on 68)

The method of claim 68, wherein the gain fiber comprises a single cladding or a double cladding.

### Claim 76 (depends on 68)

The method of claim 68, wherein the gain fiber comprises a core size ranging from 5 μm to 200 μm.

### Claim 77 (depends on 68)

The method of claim 68, wherein the gain fiber comprises a numerical aperture ranging from 0.02 to 0.25.

### Claim 78 (depends on 44)

The method of claim 44, wherein the amplifier chain further comprises:
one or more amplifier units comprising:
one or more pump diodes;
a signal/pump combiner comprising an input and an output, wherein the one or more pump diodes and the amplified and stretched signal laser pulse from the output of the first amplifier stage are coupled to the input of the signal/pump combiner;
a gain fiber comprising a doped gain medium, an input, and an output, wherein the output of the signal/pump combiner is coupled to the input of the gain fiber;
a polarization maintaining isolator comprising an input and an output, wherein the output of the gain fiber is coupled to the input of the polarization maintaining isolator and the output of the polarization maintaining isolator is configured to emit the further amplified, stretched signal laser pulse.

### Claim 79 (depends on 78)

The method of claim 78, wherein the one or more pump diodes and the signal/pump combiner are multimode and the one or more amplifier units further comprises a pump stripper coupled between the gain fiber and the polarization maintaining isolator.

### Claim 80 (depends on 78)

The method of claim 78, wherein the one or more pump diodes have a wavelength ranging from 790 nm to 796 nm.

### Claim 81 (depends on 78)

The method of claim 78, wherein the one or more pump diodes have a wavelength ranging from 1200 nm to 1220 nm.

### Claim 82 (depends on 78)

The method of claim 78, wherein the one or more pump diodes have a wavelength ranging from 1570 nm to 1620 nm.

### Claim 83 (depends on 78)

The method of claim 78, wherein the doped gain medium is at least one of: Thulium, Holmium, and Thulium/Holmium.

### Claim 84 (depends on 78)

The method of claim 78, wherein the gain fiber comprises a single cladding or a double cladding.

### Claim 85 (depends on 78)

The method of claim 78, wherein the gain fiber comprises a core size ranging from 5 μm to 200 μm.

### Claim 86 (depends on 78)

The method of claim 78, wherein the gain fiber comprises a numerical aperture ranging from 0.02 to 0.25.