High Power Short Optical Pulse Source

• US 20100157419A1
• Filed: 01/18/2007
• Published: 06/24/2010
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: NKT Photonics A/S (NKT A/S)
• Original Assignee: Fianium Ltd (NKT A/S)
• Inventors: Clowes, John Redvers, Vysniauskas, Kestutis, Godfrey, Ian Michael, Grudinin, Anatoly Borisovich
• Granted Patent: US 8,379,298 B2
• Time in Patent Office: Days
• US Class Current: 359/341.310
• CPC Class Codes: G02F 1/383 of the optical fibre type
• CPC Class Codes: H01S 2301/03 Suppression of nonlinear conversion, e.g. specific design to suppress for example stimulated brillouin scattering [SBS], mainly in optical fibres in combination with multimode pumping
• 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 3/0092 Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/061 with elliptical or circular cross-section and elongated shape, e.g. rod
• CPC Class Codes: H01S 3/067 Fibre lasers
• 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 3/06758 Tandem amplifiers
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 3/1106 Mode locking
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/2308 Amplifier arrangements, e.g. MOPA
• CPC Class Codes: H01S 3/2316 Cascaded amplifiers
• CPC Class Codes: H01S 3/2375 Hybrid lasers H01S3/07 takes precedence

Abstract

The invention is directed to a high power short optical pulse source 10 comprising a master oscillator 12 and a Ytterbium doped fibre amplifier (YDFA) preamplifier 14, a pump light source 16, an optical head 18, high power optical fibre amplifier means 20, an optical signal delivery fibre 22, and a pump light delivery fibre 24. The master oscillator 12, preamplifier 14, and pump laser 16, together with their associated drive and control electronics, and cooling systems, are provided within a first enclosure 28 at a first location. The high power fibre amplifier means 20 comprises a Ytterbium doped amplifier fibre and a pump signal combiner. The high power fibre amplifier means 20 is provided within the optical head 18, which is located at a second location, remote from the first location. The optical head 18 has a small footprint and can be positioned at the intended target of the optical pulses. The large, noisy elements of the high power short optical pulse source 10 are thereby provided away from the application site of the pulses.

Claims

1. A high power short optical pulse source comprising:

an optical signal source operable to output short optical pulses;

an optical pump light source provided at a first location;

an optical head provided at a second location remote from the first location;

high power optical fibre amplifier means having at least its optical output located within the optical head;

an optical signal delivery fibre arranged to deliver optical pulses from the optical signal source to the high power optical fibre amplifier means; and

a pump light delivery fibre arranged to deliver optical pump light to the high power optical fibre amplifier means,

wherein short optical pulses of a first optical power are delivered to the high power optical fibre amplifier means and are amplified therein to a second, high optical power for output from the optical head.

2. A high power short optical pulse source as claimed in claim 1, wherein the optical signal source comprises a master oscillator optically coupled to an optical fibre preamplifier, comprising a preamplifier amplifier optical fibre and one or more preamplifier optical pump sources.

3. A high power short optical pulse source as claimed in claim 1, wherein the optical signal source is provided at the first location.

4. A high power short optical pulse source as claimed in claim 1, wherein the master oscillator and the preamplifier amplifier optical fibre are provided at a third location, intermediate the first and second locations, with the or each preamplifier optical pump source being provided at the first location and being coupled to the preamplifier amplifier optical fibre via a corresponding one or more preamplifier pump delivery fibres.

5. A high power short optical pulse source as claimed in claim 1, wherein a plurality of optical pump light sources are provided at the first location and a corresponding plurality of pump light delivery fibres.

6. A high power short optical pulse source as claimed in claim 1, wherein the high power optical fibre amplifier means comprises an amplifier optical fibre and one or more pump signal combiners.

7. A high power short optical pulse source as claimed in claim 6, wherein the high power short optical pulse source comprises a plurality of high power optical fibre amplifier means optically coupled in series, with at least the optical output of the final high power optical fibre amplifier means being located within the optical head.

8. A high power short optical pulse source as claimed in claim 6, wherein the or each amplifier optical fibre is located within the optical head.

9. A high power short optical pulse source as claimed in claim 8, wherein the or each pump signal combiner is located within the optical head.

10. A high power short optical pulse source as claimed in claim 8, wherein the or each pump signal combiner is located at the first location, with the high power optical fibre amplifier means additionally comprising a pump signal delivery fibre optically coupled between the or each pump signal combiner and the or each amplifier optical fibre.

11. A high power short optical pulse source as claimed in claim 6, wherein the amplifier optical fibre is arranged to extend from the first location to the optical head and comprises a double-clad amplifier optical fibre.

12. A high power short optical pulse source as claimed in claim 11, wherein the or a pump signal combiner is provided at the first location, arranged to couple optical pulses and pump light into one end of the amplifier optical fibre.

13. A high power short optical pulse source as claimed in claim 12, wherein the or a pump signal combiner is provided within the optical head, arranged to couple pump light into the signal output end of the amplifier optical fibre.

14. A high power short optical pulse source as claimed in claim 6, wherein the high power optical fibre amplifier means further comprises a bulk optic amplifier element optically coupled to the output end of the or the final amplifier optical fibre, said amplifier optical fibre being under-length such that a proportion of any pump light coupled into said amplifier optical fibre is unabsorbed by it, and serves to pump the bulk optic amplifier element.

15. A high power short optical pulse source as claimed in claim 1, wherein the high power short optical pulse source further comprises nonlinear optical frequency conversion means optically coupled to the output of the or the final high power optical fibre amplifier means.

16. A high power short optical pulse source as claimed in claim 1, wherein the high power short optical pulse source comprises an optical pulse compressor optically coupled to the output of the or the final high power optical fibre amplifier means or the nonlinear optical frequency conversion means.

17. A high power short optical pulse source as claimed in claim 16, wherein the optical pulse compressor comprises a transmission grating pair or photonic crystal fibre having anomalous dispersion at the signal wavelength.

18. A high power short optical pulse source as claimed in claim 1, wherein the high power short optical pulse source further comprises a pulse picker operable to reduce the optical pulse frequency.

19. A high power short optical pulse source as claimed in claim 1, wherein the high power short optical pulse source further comprises optical monitoring means within the optical head.

20. A high power short optical pulse source as claimed in claim 1, wherein the optical head is movably mounted to enable accurate direction of generated high power short optical pulses onto a target or specimen under test.

21-22. -22. (canceled)