MODULAR FIBER-BASED CHIRPED PULSE AMPLIFICATION SYSTEM

• US 20100188736A1
• Filed: 04/06/2010
• Published: 07/29/2010
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: GU, Xinhua, LIU, Zhenlin, HARTER, Donald J., ULRICH, Otho E. JR., CHO, Gyu Choen
• Granted Patent: US 8,873,594 B2
• Time in Patent Office: Days
• US Class Current: 359/341.300
• CPC Class Codes: H01S 3/0014 Monitoring arrangements not otherwise provided for photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003
• CPC Class Codes: H01S 3/005 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 Class Codes: H01S 3/0057 Temporal shaping, e.g. pulse compression, frequency chirping soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108
• CPC Class Codes: H01S 3/0064 Anti-reflection devices, e.g. optical isolaters absorbing layers for marking or protecting purposes in laser working B23K26/50; magneto-optical non-reciprocal devices G02F1/093, G02F1/0955
• CPC Class Codes: H01S 3/0078 Frequency filtering
• CPC Class Codes: H01S 3/0085 Modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 3/02 Constructional details housings or packages of fibre lasers H01S3/06704
• CPC Class Codes: H01S 3/025 of solid state lasers, e.g. housings or mountings
• CPC Class Codes: H01S 3/06704 Housings; Packages
• CPC Class Codes: H01S 3/06712 Polarising fibre; Polariser
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/094011 with bidirectional pumping, i.e. with injection of the pump light from both two ends of the fibre
• CPC Class Codes: H01S 3/0941 of a laser diode
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/1001 by controlling the optical pumping
• CPC Class Codes: H01S 3/1028 by controlling the temperature
• CPC Class Codes: H01S 3/1115 using intracavity saturable absorbers
• CPC Class Codes: H01S 3/13013 by controlling the optical pumping
• CPC Class Codes: H01S 3/1305 Feedback control systems
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/2316 : Cascaded amplifiers
• CPC Class Codes: H01S 5/0612 : controlled by temperature
• CPC Class Codes: H01S 5/06804 : by monitoring an external parameter, e.g. temperature

Abstract

A modular ultrafast pulse laser system is constructed of individually pre-tested components manufactured as modules. The individual modules include an oscillator, pre-amplifier and power amplifier stages, a non-linear amplifier, and a stretcher and compressor. The individual modules can typically be connected by means of simple fiber splices.

Claims

1. A pulsed laser system, comprising:

a signal source;

a stretcher temporally stretching an output of said source;

a fiber amplifier;

a compressor recompressing an output of said amplifier;

an AOM selecting output pulses from said amplifier;

wherein each of said signal source, said stretcher, said fiber amplifier, said AOM and said compressor comprise a pre-tested module, and said system is configured with at least said signal source, said stretcher, said fiber amplifier and said AOM optically connected via fiber splices;

at least one tap unit within or between ones of said modules, including means for picking off a portion of said signal for measurement of an optical pulse characteristic within or between said modules, wherein said at least one tap unit provides a small signal output to a diagnostic means, said small signal output being provided during manufacturing or service of said pulsed laser system; and

an attenuator module disposed between said signal source and said stretcher, said attenuator controlling an amplitude of a pulse emitted from said source so as to prevent non-linear effects within said stretcher from altering a pulse spectrum.

2. The pulsed laser system as claimed in claim 1, wherein said filter is packaged within a filter-attenuator (F1/Attn) module.

3. The pulsed laser system as claimed in claim 1, wherein said signal source comprises a fiber oscillator, and said at least one tap unit provides a small signal output for measurement of said oscillator spectrum.

4. The pulsed laser system as claimed in claim 1, further comprising:

at least one isolator module between said signal source and said fiber amplifier for providing at least 35 dB isolation therebetween.

5. The pulsed laser system as claimed in claim 1, wherein said at least one tap unit provides a small signal output representative of pump power from a pump diode source, said small signal output providing an input for a feedback loop to regulate the pump diode source.

6. The pulsed laser system as claimed in claim 1, said system comprising at least one spectral filter, said at least one spectral filter being disposed externally to said signal source and said fiber amplifier, and either before or after said stretcher, said filter having a wavelength sensitive characteristic that modifies a spectral shape of an output from said signal source and narrows the spectrum of the signal source output, wherein at least one of said tap units is located downstream of said filter and configured to enable measurement of said narrowed spectrum, and wherein said filter is disposed before said stretcher.

7. A pulsed laser system, comprising:

a signal source;

a stretcher temporally stretching an output of said source;

a fiber amplifier;

a compressor recompressing an output of said amplifier;

an AOM selecting output pulses from said amplifier;

wherein each of said signal source, said stretcher, said fiber amplifier, said AOM and said compressor comprise a pre-tested module, and said system is configured with at least said signal source, said stretcher, said fiber amplifier and said AOM optically connected via fiber splices;

at least one tap unit within or between ones of said modules, said tap unit configured to produce a relatively small optical signal to be picked off as a diagnostic during manufacturing or service of said pulsed laser system; and

an attenuator module disposed between said signal source and said stretcher, said attenuator controlling an amplitude of a pulse emitted from said source so as to prevent non-linear effects within said stretcher from altering the pulse spectrum.

8. The pulsed laser system as claimed in claim 7, wherein said small signal output is representative of a signal spectrum within or between said modules.

9. The pulsed laser system as claimed in claim 7, wherein said at least one tap unit provides a small signal output representative of pump power from a pump diode source, said small signal output providing an input for a feedback loop to regulate the pump diode source.

10. The pulsed laser system as claimed in claim 7, said system comprising at least one spectral filter, said at least one spectral filter being disposed external to said signal source and said fiber amplifier, and either before or after said stretcher, said filter having a wavelength sensitive characteristic that modifies a spectral shape of an output from said signal source and narrows the spectrum of the signal source output, wherein at least one of said tap units is located downstream of said filter and configured to enable measurement of said narrowed spectrum, and wherein said filter is disposed before said stretcher.

11. A pulse laser system composed of a plurality of replaceable modules, comprising;

an ultrafast oscillator module;

a nonlinear amplifier module receiving the oscillator output and amplifying the signal while broadening its spectral width;

an isolator module for eliminating feedback into the oscillator;

a stretcher module for temporally stretching the output of said isolator/polarizer oscillator;

a linear pre-amplifier module for amplifying the stretched output;

a down-counter module for controlling the repetition rate of the laser system;

a power amplifier module for amplifying the output of the down-counter module; and

a compressor for temporally shortening the output of said power amplifier module.

12. A pulse laser system composed of a plurality of replaceable modules, comprising;

an ultrafast oscillator module;

a stretcher module for temporally stretching the output of said oscillator module;

a spectral filter module placed before or after said stretcher module and external to said oscillator module, said spectral filter module optically connected to said ultrafast oscillator module and comprising at least one spectral filter having a wavelength sensitive characteristic that modifies a spectral shape of an output from said ultrafast oscillator, including a spectral width of said output;

at least one pre-amplifier module downstream of said spectral filter module;

a down-counter module for reducing the repetition rate of the laser system;

a power amplifier module for amplifying the output of the down-counter module; and

a compressor for temporally shortening the output of said power amplifier module.

13. A pulse laser system, comprising the following components:

a signal source;

a stretcher temporally stretching an output of said source;

a fiber amplifier; and

a compressor recompressing an output of said amplifier; and

an AOM selecting output pulses from said amplifier;

wherein each of said components comprise a pre-tested module, and said system is configured with at least said signal source, said stretcher, said fiber amplifier and said AOM optically connected via fiber splices;

at least one tap unit within or between ones of said modules, including means for picking off a portion of said signal for enabling measurement of a spectrum within or between said modules, and

at least one spectral filter, said at least one spectral filter being disposed external to said signal source and said fiber amplifier, and either before or after said stretcher, said filter having a wavelength sensitive characteristic that modifies a spectral shape of an output from said signal source and narrows the spectrum of the signal source output;

wherein at least one of said tap units is located downstream of said filter and configured to enable measurement of said narrowed spectrum.

14. An all-fiber chirped pulse amplifier system composed of a plurality of modular optical subassemblies, comprising;

at least an oscillator module, a stretcher module, and an amplifier module, each subject to separate assembly and test, at least said oscillator module, said stretcher module and said amplifier module being coupled into the system by a fiber splice;

means located between respective ones of said modules for connecting test equipment for monitoring at least one of spectrum and pulse quality at each location, at least to identify uncompressible pulse components, the number of said means for connecting test equipment is at least one, but less than the number of said modular subassemblies and

means located between respective ones of said modules for improving fidelity of the polarization state, where the number of said means for improving fidelity of the polarization state is at least one, but less than the number of said modular subassemblies.

15. A chirped-pulse amplification system, comprising;

an ultrafast oscillator module;

a spectral filter narrowing a spectrum of a signal output from said oscillator;

at least one amplifier module;

a down-counter module;

a compressor module; and

means between ones of said modules for improving fidelity of the polarization state