Broadband or mid-infrared fiber light sources

• US 8,670,642 B2
• Filed: 01/25/2013
• Issued: 03/11/2014
• Est. Priority Date: 11/18/2005
• Status: Expired due to Fees

• Current Assignee: Omni Medsci, Inc.
• Original Assignee: Omni Medsci, Inc.
• Inventors: Islam, Mohammed N.
• Primary Examiner(s): PAK, SUNG H
• Application Number:
  US13/750,556
• Publication Number:
  US 20140001364A1
• Time in Patent Office: 410 Days
• Field of Search: None
• US Class Current: 385/122
• CPC Class Codes: G01B 9/02091 Tomographic interferometers, e.g. based on optical coherence
• CPC Class Codes: G01J 2003/102 Plural sources
• CPC Class Codes: G01J 2003/423 Spectral arrangements using lasers, e.g. tunable
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0245 using an optical amplifier of light, e.g. doped fiber
• CPC Class Codes: G01J 3/108 for measurement in the infrared range
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G02B 6/29349 Michelson or Michelson/Gires-Tournois configuration, i.e. based on splitting and interferometrically combining relatively delayed signals at a single beamsplitter
• CPC Class Codes: G02F 1/3528 for producing a supercontinuum
• CPC Class Codes: G02F 1/365 in an optical waveguide structure G02F1/377, G02F1/395 take precedence
• CPC Class Codes: G02F 2202/32 Photonic crystals
• CPC Class Codes: H01S 2301/085 solitons
• CPC Class Codes: H01S 3/06725 Fibre characterized by a specific dispersion, e.g. for pulse shaping in soliton lasers or for dispersion compensating [DCF]
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/094007 Cladding pumping, i.e. pump light propagating in a clad surrounding the active core
• CPC Class Codes: H01S 3/094069 Multi-mode pumping
• CPC Class Codes: H01S 3/094076 Pulsed or modulated pumping H01S3/1024 takes precedence
• CPC Class Codes: H01S 3/1024 for pulse generation
• CPC Class Codes: H01S 3/302 in an optical fibre
• CPC Class Codes: H01S 5/0064 Anti-reflection components, e.g. optical isolators
• CPC Class Codes: H01S 5/0085 : for modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 5/0092 : for nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity
• CPC Class Codes: H01S 5/1092 : Multi-wavelength lasing
• CPC Class Codes: H01S 5/146 : using a fiber as external cavity
• CPC Class Codes: H01S 5/4012 : Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms

Abstract

An optical system for use in a spectroscopy procedure includes one or more semiconductor diodes configured to generate an input signal beam with a wavelength shorter than 2.5 microns that is amplified and communicated through optical fiber(s) to a nonlinear element configured to broaden the spectral width to at least 50 nm through a nonlinear effect. A subsystem includes lenses or mirrors to deliver an output beam having a broadened spectrum selected to obtain a desired penetration depth and substantially minimize water absorption with a temporal duration greater than about 30 picoseconds to a sample to perform spectroscopy to characterize the sample. The output beam may have a repetition rate between continuous wave and one Megahertz or higher with a time averaged output power of 20 mW or more and a time averaged intensity of less than approximately 50 MW/cm².

Claims

1. An optical system for use in a spectroscopy procedure, the system comprising:

one or more semiconductor diodes configured to generate an input beam, wherein at least a portion of the input beam comprises a wavelength shorter than 2.5 microns;

one or more optical amplifiers configured to receive at least the portion of the input beam and to communicate an intermediate beam to an output end of the one or more optical amplifiers;

one or more optical fibers configured to receive at least a portion of the intermediate beam and to communicate at least the portion of the intermediate beam to a distal end of the one or more optical fibers to form a first optical beam;

a nonlinear element configured to receive at least a portion of the first optical beam and to broaden a spectrum associated with the at least a portion of the first optical beam to at least 50 nm through a nonlinear effect in the nonlinear element to form an output beam with an output beam broadened spectrum; and

a subsystem comprising one or more lenses or mirrors configured to receive at least a portion of the output beam and to deliver at least the portion of the output beam to a sample to perform spectroscopy for characterizing the sample, wherein at least a portion of the output beam broadened spectrum that substantially minimizes water absorption, wherein the at least a portion of the output beam has a temporal duration greater than approximately 30 picoseconds, wherein at least the portion of the output beam has a repetition rate between continuous wave and Megahertz or higher, wherein a time averaged output power of the output beam is 20 mW or more, and wherein a time averaged intensity of the at least a portion of the output beam is less than approximately 50 MW/cm².

2. The system of claim 1, wherein at least a portion of the one or more optical amplifiers comprises a cladding-pumped fiber amplifier doped with rare-earth materials.

3. The system of claim 1, wherein the at least a portion of the output beam broadened spectrum is further selected to obtain a desired penetration depth, and wherein at least the portion of the output beam has a temporal duration greater than approximately 100 picoseconds.

4. The system of claim 1, wherein the spectroscopy is Fourier Transform Infrared (FTIR), absorption or reflection.

5. The system of claim 1, wherein the spectroscopy for characterizing the sample comprises spectral fingerprinting, wherein at least the portion of the output beam broadened spectrum is used to illuminate substantially simultaneously a number of spectral features and wherein the sample is identified by the number of spectral features.

6. The system of claim 1, wherein the spectroscopy for characterizing the sample comprises identification of the sample based at least in part on its chemical composition, and wherein the spectroscopy for characterizing the sample is performed on overtone or combinational bands.

7. The system of claim 1, wherein the spectroscopy comprises at least in part a filter based spectroscopy in a point detection apparatus that further comprises one or more dispersive optics, slits and detectors.

8. The system of claim 1, wherein at least a portion of the nonlinear element is a photonic crystal fiber.

9. A method of performing optical spectroscopy comprising:

generating an input beam, wherein at least a portion of the input beam comprises a wavelength shorter than 2.5 microns and an input optical spectral width;

amplifying the at least a portion of the input beam;

broadening the input optical spectral width to at least 50 nm through a nonlinear effect in a nonlinear element;

forming an output beam with an output beam broadened spectrum;

receiving and delivering at least a portion of the output beam to a sample; and

performing spectroscopy to characterize the sample, wherein at least a portion of the output beam broadened spectrum that substantially minimizes water absorption, wherein at least the portion of the output beam has a temporal duration greater than approximately 30 picoseconds, wherein the at least a portion of the output beam has a repetition rate from continuous wave to Megahertz or higher, wherein a time averaged output power of the output beam is 20 mW or more, and wherein a time averaged intensity of the at least a portion of the output beam is less than approximately 50 MW/cm².

10. The method of claim 9, wherein the spectroscopy is Fourier Transform Infrared (FTIR), absorption or reflection.

11. The method of claim 9, wherein the spectroscopy to characterize the sample comprises spectral fingerprinting, wherein at least the portion of the output beam broadened spectrum is used to produce substantially simultaneously a number of spectral features and wherein the sample is identified by the number of spectral features.

12. The method of claim 9, wherein the spectroscopy for characterizing the sample comprises identification of the sample based at least in part on its chemical composition, and wherein the spectroscopy for characterizing the sample is performed on overtone or combinational bands.

13. The method of claim 9, wherein the spectroscopy comprises at least in part a filter based spectroscopy in a point detection apparatus that further comprises one or more dispersive optics, slits and detectors, and wherein at least a portion of the nonlinear element is a photonic crystal fiber.

20. The method of claim 9, wherein the at least a portion of the output beam broadened spectrum is further selected to obtain a desired penetration depth, and wherein the at least a portion of the output beam has a temporal duration greater than approximately 100 picoseconds.

14. An optical system for use in a spectroscopy procedure, the system comprising:

a plurality of semiconductor diodes, each of the diodes configured to generate an optical beam;

a beam combiner configured to receive at least a portion of the optical beams from the plurality of semiconductor diodes and to generate a multiplexed optical beam;

an optical fiber configured to receive at least a portion of the multiplexed optical beam and to communicate the at least a portion of the multiplexed optical beam to form an intermediate beam having at least one wavelength;

a light guide configured to receive at least a portion of the intermediate beam and to propagate the at least a portion of the intermediate beam to form an output beam; and

a subsystem comprising one or more lenses or mirrors configured to receive at least a portion of the output beam and to deliver the at least a portion of the output beam to a sample to perform spectroscopy for characterizing the sample, wherein a wavelength associated with the at least a portion of the output beam that substantially minimizes water absorption, wherein the at least a portion of the output beam has a temporal duration greater than approximately 30 picoseconds, wherein the at least a portion of the output beam has a repetition rate from continuous wave to a Megahertz or higher, wherein a time averaged output power of the output beam is 20 mW or more, and wherein a time averaged intensity of the portion of the output beam is less than approximately 50 MW/cm².

15. The optical system of claim 14, wherein at least a portion of the optical fiber comprises a cladding-pumped fiber amplifier doped with rare-earth materials.

16. The optical system of claim 14, wherein the spectroscopy is Fourier Transform Infrared (FTIR), absorption or reflection.

17. The optical system of claim 14, wherein the spectroscopy for characterizing the sample comprises spectral fingerprinting, wherein the wavelength of the at least a portion of the output beam is used to produce substantially simultaneously a number of spectral features and wherein the sample is identified by the number of spectral features.

18. The optical system of claim 14, wherein the spectroscopy for characterizing the sample comprises identification of the sample based at least in part on its chemical composition, and wherein the spectroscopy for characterizing the sample is performed on overtone or combinational bands.

19. The optical system of claim 14, wherein the spectroscopy comprises at least in part a filter based spectroscopy in a point detection apparatus that further comprises one or more dispersive optics, slits and detectors, and wherein at least a part of the light guide is a photonic crystal fiber.