BROADBAND OR MID-INFRARED FIBER LIGHT SOURCES

• US 20090028193A1
• Filed: 11/15/2006
• Published: 01/29/2009
• Est. Priority Date: 11/18/2005
• Status: Active Grant

• Current Assignee: Omni Continuum LLC
• Original Assignee: Omni Sciences Incorporated
• Inventors: Islam, Mohammed N.
• Granted Patent: US 7,519,253 B2
• Time in Patent Office: Days
• US Class Current: 372/6
• 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

A broadband light source includes one or more laser diodes that are capable of generating a pump signal having a wavelength shorter than 2.5 microns, a pulse width of at least 100 picoseconds and a pump optical spectral width. The light source also includes one or more optical amplifiers that are coupled to the pump signal and are capable of amplifying the pump signal to a peak power of at least 500 W. The light source further includes a first fiber that is coupled to the one or more optical amplifiers. The first fiber including an anomalous group-velocity dispersion regime and a modulational instability mechanism that operates to modulate the pump signal. In one particular embodiment, the pump signal wavelength resides in the anomalous group-velocity dispersion regime of the first fiber and where different intensities in the pump signal can cause relative motion between different parts of the modulated pump signal produced through modulational instability in the first fiber. The light source also including a nonlinear element that is coupled to the first fiber that is capable of broadening the pump optical spectral width to at least 100 nm through a nonlinear effect in the nonlinear element.

Claims

1. A broadband light source comprising:

one or more laser diodes capable of generating a pump signal comprising a wavelength shorter than 2.5 microns, a pulse width of at least 100 picoseconds and a pump optical spectral width;

one or more optical amplifiers coupled to the pump signal and capable of amplifying the pump signal to a peak power of at least 500 W;

a first fiber coupled to the one or more optical amplifiers, the first fiber comprising an anomalous group-velocity dispersion regime and a modulational instability mechanism that modulates the pump signal, wherein the pump signal wavelength resides in the anomalous group-velocity dispersion regime of the first fiber, and wherein different intensities in the pump signal can cause relative motion between different parts of the modulated pump signal produced through modulational instability in the first fiber; and

a nonlinear element coupled to the first fiber capable of broadening the pump optical spectral width to at least 100 nm through a nonlinear effect in the nonlinear element.

2. The broadband light source of claim 1, wherein the one or more optical amplifiers are selected from the group consisting of a rare-earth doped fiber amplifier, a thulium-doped fiber amplifier, an erbium-doped fiber amplifier, a semiconductor optical amplifier, a Raman amplifier, and a cladding pumped fiber amplifier.

3. The broadband light source of claim 1, wherein the first fiber is selected from the group consisting of a fused silica fiber, a standard single-mode fiber, a high-nonlinearity fiber, a dispersion-shifted fiber, a non-zero dispersion shifted fiber, a microstructure fiber and a dispersion compensating fiber.

4. The broadband light source of claim 1, wherein the nonlinear element is selected from the group consisting of a high-nonlinearity fiber, a dispersion-compensating fiber, a ZBLAN fiber, a fluoride fiber, a tellurite fiber, a chalcogenide fiber, a semiconductor waveguide, a PIN silicon waveguide, a photonic crystal fiber, and a hollow core fiber filled with a nonlinear liquid or gas.

5. The broadband light source of claim 1, wherein the nonlinear element comprises a length 15 meters or less.

6. The broadband light source of claim 1, wherein the nonlinear effect of the nonlinear element is selected from the group consisting of self-phase modulation, self-steepening, a Raman effect, four-wave mixing, and cross-phase modulation.

7. The broadband light source of claim 1, further comprising one or more optical filters coupled to the one or more optical amplifiers to control a level of amplified spontaneous emission, wherein the one or more optical filters are selected from the group consisting of spectral filters and temporal filters.

8. The broadband light source of claim 1, wherein at least a portion of the one or more optical amplifiers comprises a cladding-pumped fiber amplifier pumped by a plurality of multi-mode pump lasers comprising at least a second wavelength, wherein the second wavelength is substantially different than the pump signal wavelength.

9. The broadband light source of claim 1, wherein a long wavelength edge of the pump optical spectral width after the nonlinear element is at substantially 2.6 microns or longer.

10. The broadband light source of claim 1, wherein a center wavelength for the pump optical spectral width after the nonlinear element is capable of being adjusted by a device selected from the group consisting of dispersion management in the nonlinear element and a seed laser.

11. The broadband light source of claim 1, wherein the light source is used in a last mile telecommunications system by coupling the light source to one or modulators and a wavelength separator.

12. A mid-infrared light source comprising:

one or more laser diodes capable of generating a pump signal comprising at least one wavelength and a pulse width of at least 100 picoseconds;

one or more optical amplifiers coupled to the pump signal and capable of amplifying the pump signal;

one or more fibers coupled to the one or more optical amplifiers, at least one of the one or more fibers comprising an anomalous group-velocity dispersion regime and a modulational instability mechanism that modulates the at least one wavelength of the pump signal in at least a portion of the at least one of the one or more fibers, wherein the at least one wavelength of the pump signal resides in the anomalous group-velocity dispersion regime for at least a fraction of the at least one of the one or more fibers; and

a nonlinear element coupled to the one or more fibers capable of generating a super-continuum with a substantially continuous spectrum from at least the at least one wavelength of the pump signal to 2.6 microns or longer and wherein the nonlinear element introduces less than 10 decibels of power loss at 2.6 microns.

13. The light source of claim 12, wherein at least a portion of the one or more amplifiers is a rare-earth doped fiber amplifier, wherein at least a portion of the one or more fibers is fused silica fiber, and wherein at least a portion of the nonlinear element is a light guide selected from the group consisting of a high-nonlinearity fiber, a dispersion-compensating fiber, a ZBLAN fiber, a fluoride fiber, a tellurite fiber, a chalcogenide fiber, a semiconductor waveguide, a PIN silicon waveguide, a photonic crystal fiber, and a hollow core fiber filled with a nonlinear liquid or gas.

14. The light source of claim 12, wherein the super-continuum is used to emulated at least in part a black body radiation from a heated object or in a spectral fingerprinting system, where the substantially continuous spectrum is used to monitor substantially simultaneously a number of absorption lines and wherein a chemical species is identified by a pattern of absorption lines.

15. The light source of claim 14, wherein a signal-to-noise ratio is increased by selectively rejecting noise during times when the super-continuum is not emitted using a technique selected from the group consisting of a time modulation technique and a time gated detection technique.

16. The light source of claim 12, wherein at least a part of the one or more optical amplifiers is a cladding-pumped fiber amplifier pumped by a plurality of multi-mode pump lasers comprising at least a second wavelength different than the at least one wavelength of the pump signal.

17. A method of generating broadband light comprising the steps of:

generating a pump signal, wherein the pump signal comprises at least one wavelength shorter than 2.5 microns, a pulse width of at least 100 picoseconds and a pump optical spectral width;

amplifying the pump signal to a peak power of at least 500 watts;

modulating at least a fraction of the pump signal using a modulational instability mechanism, wherein different intensities in the pump signal leads to relative motion between different portions of the pump signal; and

broadening the pump optical spectral width to at least 100 nm using a nonlinear effect.

18. The method of claim 17, wherein the pump signal is amplified in a cladding pumped fiber amplifier pumped by a plurality of multi-mode pump lasers comprising at least a second wavelength different than the at least one wavelength of the pump signal.

19. The method of claim 17, wherein the broadband light is used for emulating black body radiation, identifying particular chemical species, transmitting in a last mile telecommunications system, or ablating proteins or tissue in biological systems.

20. The method of claim 17, wherein a power associated with the at least 100 nm pump optical spectral width can be increased by increasing a pulse repetition rate of the pump signal.