WO2002063729A1 - Self seeded multiple wavelength generation - Google Patents

Self seeded multiple wavelength generation

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Publication number
WO2002063729A1
WO2002063729A1 PCT/US2002/003600 US0203600W WO2002063729A1 WO 2002063729 A1 WO2002063729 A1 WO 2002063729A1 US 0203600 W US0203600 W US 0203600W WO 2002063729 A1 WO2002063729 A1 WO 2002063729A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
wavelengths
apparatus
method
wavelength
optical processing
Prior art date
Application number
PCT/US2002/003600
Other languages
French (fr)
Other versions
WO2002063729A9 (en )
Inventor
Josh Hogan
Original Assignee
Frame Photonics
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING STIMULATED EMISSION
    • H01S3/00Lasers, i.e. devices for generation, amplification, modulation, demodulation, or frequency-changing, using stimulated emission, of infra-red, visible, or ultra-violet waves
    • H01S3/05Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06Construction or shape of active medium
    • H01S3/063Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067Fibre lasers
    • H01S3/0675Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING STIMULATED EMISSION
    • H01S3/00Lasers, i.e. devices for generation, amplification, modulation, demodulation, or frequency-changing, using stimulated emission, of infra-red, visible, or ultra-violet waves
    • H01S3/05Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08Construction or shape of optical resonators or components thereof
    • H01S3/08086Multiple-wavelength emission
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING STIMULATED EMISSION
    • H01S3/00Lasers, i.e. devices for generation, amplification, modulation, demodulation, or frequency-changing, using stimulated emission, of infra-red, visible, or ultra-violet waves
    • H01S3/10Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/10084Frequency control by seeding
    • H01S3/10092Coherent seed, e.g. injection locking
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING STIMULATED EMISSION
    • H01S3/00Lasers, i.e. devices for generation, amplification, modulation, demodulation, or frequency-changing, using stimulated emission, of infra-red, visible, or ultra-violet waves
    • H01S3/10Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/106Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling a device placed within the cavity
    • H01S3/108Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling a device placed within the cavity using a non-linear optical device, e.g. exhibiting Brillouin- or Raman-scattering
    • H01S3/1083Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling a device placed within the cavity using a non-linear optical device, e.g. exhibiting Brillouin- or Raman-scattering using parametric generation

Abstract

This invention provides a means for generating multiple wavelengths in an integrated manner in a non-linear dispersion shifted medium (105) by means of seeding the desired wavelengths with radiation reflected by the reflective Bragg gratings (501, 502). The process is powered by one or more high power laser sources (101) that emit radiation at a particular wavelength. This radiation propagateS through a highly non-linear medium with Bragg gratings (501, 502) designed to reflect at the wavelength values of the desired wavelength set. An optical modulator (104) modulates the laser radiation at a frequency harmonically related to the frequency separation of the desired wavelength set. The combination of the reflecting gratings (501, 502) and the harmonically related modulation seed the generation of desired wavelength set and provide a method of stabilizing the set,

Description

Self Seeded Multiple Wavelength Generation

Inventor: Josh Hogan

Patent Application Number 20009

Background of the Invention

This invention relates to the area of optical sources which provide output radiation at a multiplicity of wavelengths. This has application in such areas as the optical communications industry where Dense Wavelength Division Multiplexing (DWDM) achieves high data rate transmission by independently modulating data on to a multiplicity of optical beams, each with a different wavelength. The actual values of these wavelengths correspond to specific values defined by industry standards and often referred to as the ITU grid. These optical beams are typically independently modulated with a data signal and then combined and propagated down a single optical fiber. Since the different wavelengths do not significantly interfere with each other the multiple wavelengths are effectively independent communications channels.

Multiple wavelength sources are typically generated by having multiple laser diodes each designed to emit at one of the required wavelengths. Each laser diode may be fabricated so that it emits at a particular wavelength as in the case of Distributed Feed Back (DFB) lasers where the emitting wavelength is determined by the physical spacing of a distributed Bragg grating that is part of the laser diode. Alternately, laser diodes may be fabricated that are capable of emitting over a broad wavelength range and are tuned to a particular wavelength by means of precision temperature control, precision cavity length control or other means.

An alternative approach to generating multiple wavelengths is to generate a continuum of wavelengths by applying a high power single wavelength source for four wave mixing in a nonlinear medium such as fiber. The non-linear or anharmonic characteristics allow the transformation of the source or pump radiation to other wavelengths.

High power is typically achieved by using a pulsed optical source so that high peak power can be attained with relatively low average power. The spectrum of the input optical pulse will be broadened to provide a continuum of wavelengths. The width of this continuum can be large if long lengths of conventional fiber are used. More recently "photonic crystal fiber" allows an extremely large continuum range to be generated with a relatively short length of fiber. A set of individual wavelengths can be generated from this continuum by routing the optical beam through a set of optical filters, such as distributed fiber gratings. This approach of generating a set of multiple wavelengths by filtering a continuum is inherently inefficient because the wavelengths filtered out essentially are wasted energy.

Another approach described at the SPIE Conference on Optical Fiber Communications, Taipei, Taiwan, July 1998 in a paper titled A Multi-wavelength WDM Source Generated by Four-Wave- Mixing in a Dispersion-Sbifted-Fiber by Keang-Po Ho and Shien-Kuei Liaw is to combine the output of two continuous wave laser diodes that have slightly different wavelengths, amplify the combined signal with a high power Erbium Distributed Fiber Amplifier (EDFA) and apply this to a dispersion shifted fiber for four way mixing to produce a set or comb of wavelengths, whose wave length separation is determined by the difference in wavelength of the two seed laser diodes. Dispersion of a medium refers to the variation of the speed of propagation of radiation with wavelength within the medium. Typically the optical dispersion of a medium exhibits one or more minima at specific wavelengths around which the variation of speed of propagation with wavelength is small. Dispersion shifted media, such as, dispersion shifted fiber is designed to have zero dispersion close to the desired operating wavelength. (For the purpose of this application, dispersion shifted medium is also intended to include the situation where a minimum coincides with the desired operating wavelength without specific modification.) This approach, however, still requires a physically long amount of dispersion shifted medium, which requires the system to be physically large which makes it more subject to environmental changes and not compatible with a requirement of being compact. It also requires the use of an expensive EDFA.

An alternative approach that addresses these problems is described in two US patent applications Express Mail Label No. EF246731316 US, Filing Date 8th. Dec 2000, Internal No. JH20003 & Express Mail Label No. EF246731418 US, Filing Date 8th. Dec 2000, Internal No. JH20004 . The disclosure of these US patent applications are hereby incorporated herein by reference. This approach involves such techniques as using a single gain switched laser diode to provide high peak power and using a combination of reflective fiber Bragg gratings designed to reflect at the desired wavelength values, a harmonically related optical pulse repetition rate and a resonant cavity in which the round trip time is also harmonically related to the pulse repetition rate and the frequency separation of the wavelength set While this approach addresses the problem of achieving high peak power by gain switching the laser diode, this has the undesirable requirement of generating and pulsing the laser diode with short, high energy current pulses. This requirement limits the number of wavelengths that can be generated with, significant power per wavelength. This is particularly important as the optical communications industry moves from requiring 40 individual wavelengths to requiring 192 wavelengths and more for future generations. Furthermore the emergence of higher power laser diodes for such purposes as optical amplifier pump sources is providing a technical route to high optical power. These sources are, however, typically incompatible with high frequency gain switching.

Therefore there is an unmet need for an efficient compact method and apparatus for generating a stabilized set or comb of wavelengths in manner that is compatible with low cost fabrication, which provides an integrated source of radiation at multiple wavelengths and which can be scaled to a large number of wavelengths each with a relatively high power. Summary of the Invention

This invention provides a means for generating multiple wavelengths in an integrated manner using a high power laser diode and highly non-linear dispersion shifted medium with reflective Bragg gratings. The combination of a high powered laser source and a highly non-linear medium allows efficient transformation of the source optical power into the desired set of multiple wavelengths by means of four wave mixing. Energy at the wavelengths reflected by the reflective Bragg gratings seed the mixing process so that the desired wavelength set is preferentially generated. The seeding process can be enhanced and stabilized by modulating the source optical power at a frequency that is harmonically related to the frequency separation of the desired wavelength set.

Brief Description of the Drawings

Figure 1 is an illustration of the preferred embodiment of the invention taught herein.

Figure 2 is an illustration of a typical depth of modulation profile of the Bragg gratings.

Figure 3 is an illustration of the power normalized output wavelength set.

Figure 4 is an illustration of a typical non-linear fiber with Bragg gratings.

Figure 5 is an illustration of non-linear fiber with two terminating bleed fibers.

Figure 6 is an illustration of a typical automatic stabilizing feedback system. Detailed Description of the Invention

A preferred embodiment of the invention for generating a set of discrete wavelengths is illustrated in and described with reference to Figure 1, where a high power wavelength stabilized laser diode 101 powered by a direct current electrical power source 102. The output optical radiation of the laser diode is coll mated by coupling optics 103, routed through an optical modulator 104 and focused into a non-linear fiber 105 by means of focusing optics 106. The modulator is powered by a radio frequency (RF) power source 07. The purpose of the modulator is to impose a periodic disturbance on the optical radiation with a frequency harmonically related to the frequency separation of the wavelengths that are to be generated. For example, if the frequency separation of the set were 100 GHz, a modulation frequency of 25 or 50 GHz could be imposed. More ideally the modulation frequency exactly corresponds to frequency separation of the desired wavelength set, such as both a frequency separation and modulation frequency of 25 GHz. The advantage of modulating in the optical domain (rather than electronic) is that the source laser diode can then be powered by direct current and thereby removing the significant technical task of high frequency current modulation. Optical modulation can be either amplitude or phase modulation, however phase modulation has the desirable aspect of being highly efficient, in that none of the optical energy is wasted (unlike the situation involving amplitude modulation). The wavelength of the laser diode can be wavelength stabilized by a variety of standard techniques such as distributed feedback or seeding by a low power distributed feedback laser. The wavelength stabilized, modulated optical radiation is focused into the fiber composed of non-linear processing medium. The non-linear or anhaπnonic aspect of the medium "facilitates the absorption of the source or pump radiation at its wavelength and its re-radiation at a different wavelength thus enabling the generation of additional wavelengths. With no controlling mechanism in place, the spectrum of the additional wavelengths generated will be noise like. With a control mechanism in place, the optical energy can be directed into specific wavelengths. This process is referred to as seeding and in this preferred embodiment is accomplished by means of reflective Bragg gratings 108 in figure 1 imposed on the fiber 105. The representation of the fiber 105 is intended to include multiple gratings, each intended to reflect a portion of one of the desired wavelengths. These reflected wavelengths, initially generated by a combination of noise and the imposed optical modulation, act as seeding wavelengths. These wavelengths are then preferentially generated and this process generates further wavelengths by the process of four wave mixing. This approach of seeding by means of reflected radiation has the advantage over other approaches (such as using multiple laser diodes) in that ail radiation is derived from a single coherent source, which both reduces cost and removes stability problems arising from multiple incoherent sources. The amount of optical energy generated at the different wavelengths will not be equal and would therefore lead to unequal amounts emerging from the fiber at its output 109. This issue is addressed by having correspondingly different depths of modulation in the different reflective gratings, by the order in which the gratings occur and if necessary by having multiple occurrences of at least some of the gratings. (For purposes of this disclosure, depth of modulation of a grating will be equivalent to the reflected fraction of the radiation at a particular wavelength.) A typical profile of the depth of modulation at different wavelengths is illustrated in Figure 2. The center wavelength λP 201 corresponds to the wavelength of the pump radiation. The generated wavelengths are all separated by a common frequency separation 202 ( Δv ). The ideal power normalized set of wavelengths is illustrated in figure 3. (The illustration contains nine wavelengths for example purposes only, the actual number would be a product design consideration.) Figure 4 illustrates the uncoiled fiber and depicts a reflective element 403 that substantially contain the generated wavelengths substantially within the optical processing fiber and nine reflective gratings in a typical configuration, the first of which is 401 and the last of which is 402 and is ideally the Bragg grating that reflects the pump wavelength λp . The process of four wave mixing would extend to generating wavelengths beyond the desired set This can be terminated by bleeding off wavelengths at either side of the desired wavelength set by means of two additional fibers attached to the main processing fiber. These additional fibers 501 and 502 of Figure 5 also have fiber gratings 503 and 504 designed to transmit only one wavelength, these being the two wavelengths just outside the desired wavelength set. Bleeding off these wavelengths substantially prevents the generation of other wavelengths outside desired set. Furthermore, these two wavelengths that are bled off can be detected and used for stabilization purposes.

The combination of modulating the pump optical radiation at the same frequency as the frequency separation of the desired wavelength set provides a method of stabilizing the multiple wavelength generation system. This can be accomplished by deriving the F modulating frequency from a highly accurate frequency reference. The wavelength values of the reflective gratings and therefore their frequency separation are temperature dependent. A temperature control system can therefore be used to bring the fiber containing the reflective gratings to the correct temperature. It is only at this correct temperature that the modulation effect and the four wave mixing process fully co-operate to optimize the transformation of pump radiation to the desired multiple wavelength set. Detection of this optimal condition provides a method of implementing an automatic feedback system of the type illustrated in Figure 6. The RF power source 107 in Figure 6 is driven by a highly stable frequency reference 601, harmonically related to the desired wavelength separation The processing fiber 105 is housed in a temperature controllable housing 602. Signals from the two bleeding fibers are routed to optical detectors 603 and 604 and the detected signals are analyzed in the Feedback Processing Unit 605. The processing unit 605 analyses the signals from the detectors to calculate the degree of cooperation between the modulation and the reflective Bragg gratings and uses this as an error signal to control the current 606 that establishes the temperature of the fiber. This stabilization process can be enhanced by imposing a small low frequency modulation with modulator 607 from a reference 608, on the RF reference source and exploiting this in the feed back processing unit 605. Any residual low frequency modulation on the generated wavelengths can be removed when these wavelengths are being modulated with data. In this manner the desired set of multiple wavelengths is generated in an efficient manner that allows implementation of an automatic stabilization system.

It is understood that the above description is intended to be illustrative and not restrictive. Many of the features have functional equivalents that are intended to be included in the invention as being taught. For example, the laser diode could have a fiber coupled output and be wavelength stabilized by a reflective Bragg grating and be modulated by a fiber modulator. The processing non-linear fiber could be replaced with a waveguide composed of non-linear medium with reflective Bragg gratings. Various combinations of waveguide elements and fiber based elements can be employed. Other examples will be apparent to persons skilled in the art.

The scope of this invention should therefore not be determined with reference to the above description, but instead should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

What is claimed is:
1. A method of generating radiation with a multipUcity of specific discrete wavelengths, the method comprising: positioning a multiplicity of distributed reflective elements in an optical processing medium; and propagating high power pump radiation in said optical processing medium, such that radiation with a multiplicity of specific discrete wavelengths is generated.
2. The method of claim 1 , wherein the high power radiation is generated by a high power laser diode.
3. The method of claim 2, wherein the high power laser diode is powered by a direct current electrical power source.
4. The method of claim 2, wherein the wavelength of the pump radiation emitted by the high power laser diode is stabilized to a particular value.
5. The method of claim 4, wherein the wavelength value of the pump radiation corresponds to a wavelength on a standard grid.
6. The method of claim 5, wherein the standard grid is an optical communications ITU grid.
7. The method of claim 1, wherein the pump radiation is modulated by a high frequency optical modulator driven by an RF power source operating at a particular frequency.
8. The method of claim 7, wherein the modulator is an optical phase modulator.
9. The method of claim 7, wherein the modulator is an amplitude modulator.
10. The method of claim 7, wherein the frequency of the modulator is harmonically related to the frequency corresponding to wavelength separation of the multiple discrete wavelengths.
11. The method of claim 1, wherein the optical processing medium is dispersion shifted medium.
12. The method of claim 1, wherein the optical processing medium is dispersion shifted fiber.
13. The method of claim 1, wherein the optical processing medium is photomc crystal fiber.
14. The method of claim 1, wherein the optical processing medium is photonic crystal.
15. The method of claim 1, wherein the optical processing medium is capable of producing a multiplicity of wavelengths" separated by a defined frequency difference.
16. The method of claim 1, wherein the optical processing medium has zero dispersion centered on the desired multiplicity of wavelengths.
17. The method of claim 1, wherein the optical processing medium is highly non-linear medium.
18. The method of claim 15, wherein the defined frequency difference that separates the wavelengths of the generated wavelength set corresponds to a frequency separation on a standard grid.
19. The method of claim 18 wherein the standard grid is an optical communications ITU grid.
20. The method of claim 1, wherein the reflective elements are distributed Bragg gratings.
21. The method of claim 1, wherein reflective elements at the pump end of the optical processing medium substantially contain the generated wavelengths within the optical processing medium.
22. The method of claim 1, wherein at least some of the reflective elements reflect a fraction of a particular wavelength related to the relative intensity of the amount of energy generated at that particular wavelength of the generated set of wavelengths.
23. The method of claim 1, wherein at least some of the reflective elements are reflective at the same wavelength value.
24. The method of claim 1, wherein at least some of the reflective elements are positioned and have a relative depth of modulation such that the generated set of wavelengths emerge from the optical processing medium with substantially the same power at each wavelength
25. The method of claim 1, wherein the reflective elements reflect radiation at least at some of the wavelengths of the set of wavelengths to be generated.
26. The method of claim 25, wherein the reflected radiation seeds further generation of these first generated wavelengths.
21. The method of claim 26, wherein reflections of the generated first wavelengths seed generation additional wavelengths.
28. The method of claim 1, wherein generating wavelengths at wavelength values outside the desired -wavelength set is suppressed by allowing the wavelengths immediately outside the generated set to substantially emerge from the optical processing medium.
29. The method of claim 28, wherein the undesired wavelengths substantially emerge from the optical processing medium by means of coupled fibers that can only propagate, undesired wavelengths.
30. The method of claim 1, wherein generated multiphciiy of wavelengths are maintained at specific values by means of a stabilizing feedback system.
31. The method of claim 30, wherein the feedback system includes temperature controlling the optical processing medium.
32. The method of claim 30, wherein the feedback system includes driving the EF modulator with a signal derived from a high stability frequency reference.
33. The method of claim 30, wherein the feedback system includes monitoring the quality of the wavelengths on either side of the desired wavelength set.
34. The method of claim 30, wherein the feedback system includes imposing a low frequency modulation on the high stability frequency reference.
35. The method of claim 34, wherein the feedback system includes monitoring the quality of the wavelength on either side of the desired wavelength set and the imposed low frequency modulation
36. The method of claim 35, wherein the effects of the low frequency modulation are compensated for when the generated wavelengths are modulated with data.
37. An apparatus for generating radiation with a multiplicity of specific discrete wavelengths, the apparatus consisting of: an optical processing element with a multiplicity of distributed reflective elements; and at least one optically active element, said optically active element operable to generate optical pump radiation and optically coupled to the optical processing element; and operable to transmit such optical pump radiation to the optical processing element; and operable to generate radiation with a multiplicity of discrete wavelengths.
38. The apparatus of claim 37, wherein the optically active element is a high power laser diode operable to generate high power laser radiation
39. The apparatus of claim 38, wherein the high power laser diode is powered by a direct current electrical power source.
40. The apparatus of claim 38, wherein the wavelength of the pump radiation emitted by the high power laser diode is stabilized to a particular value.
41. The apparatus of claim 40, wherein the wavelength value of the pump radiation corresponds to a wavelength on a standard grid.
42. The apparatus of claim 41, wherein the standard grid is an optical communications ITU grid.
43. The apparatus of claim 37, wherein the pump radiation is modulated by a high frequency optical modulator driven by an EF power source operating at a particular frequency.
44. The apparatus of claim 43, wherein the modulator is an optical phase modulator.
45. The apparatus of claim 43, wherein the modulator is an amplitude modulator.
46. The apparatus of claim 43, wherein the frequency of the modulator is harmonically related to the frequency corresponding to wavelength separation of the multiple discrete wavelengths.
47. The apparatus of claim 37, wherein the optical processing medium is dispersion shifted medium.
48. The apparatus of claim 37, wherein the optical processing medium is dispersion shifted fiber.
49. The apparatus of claim 37, wherein the optical processing medium is photonic crystal fiber.
50. The apparatus of claim 37, "wherein the optical processing medium is photomc crystal.
51. The apparatus of claim 37, wherein the optical processing medium is operable to produce a multiplicity of wavelengths separated by a defined frequency difference.
52. The apparatus of claim 37, wherein the optical processing medium has zero dispersion centered on the desired multiplicity of wavelengths.
53. The apparatus of claim 37, wherein the optical processing medium is highly non-linear medium.
54. The apparatus of claim 51, wherein the defined frequency difference that corresponds to the separation between the wavelengths of the generated wavelength set corresponds to a frequency separation on a standard grid.
55. The apparatus of claim 54, wherein the standard grid is an optical communications ITU grid.
56. The apparatus of claim 37, wherein the reflective elements are distributed Bragg gratings.
57. The apparatus of claim 37, wherein reflective elements at the pump end of the optical processing medium are operable to substantially contain the generated wavelengths within the optical processing medium.
5S. The apparatus of claim 37, wherein at least some of the reflective elements are operable to reflect a fraction of a particular wavelength related to the relative intensity of the amount of energy generated at that particular wavelength of the generated set of wavelengths.
59. The apparatus of claim 37, wherein at least some of the reflective elements are operable to reflect at the same wavelength value.
60. The apparatus of claim 37, wherein at least some of the reflective elements are positioned and have a relative depth of modulation such that the generated set of wavelengths emerge from the optical processing medium with substantially the same power at each wavelength.
61. The apparatus of claim 37, wherein the reflective elements are operable to reflect radiation at least at some of the wavelengths' of the set of wavelengths to be generated.
62. The apparatus of claim 61, wherein the reflected radiation are operable to seed further generation of these first generated wavelengths.
63. The apparatus of claim 62, wherein reflections of the generated first wavelengths are operable to seed generation additional wavelengths.
64. The apparatus of claim 37, wherein generating wavelengths at wavelength values outside the desired wavelength set is suppressed by allowing the wavelengths immediately outside the generated set to substantially emerge from the optical processing medium.
65. The apparatus of claim 64, wherein coupled fibers that can only propagate undesired wavelengths are operable to substantially remove the undesired wavelengths from the optical processing medium.
66. The apparatus of claim 37, wherein a stabilizing feedback system is operable to maintain the generated multipHciry of wavelengths at specific wavelength values.
67. The apparatus of claim 66, wherein the feedback system includes temperature controlling the optical processing medium.
68. The apparatus of claim 66, wherein the feedback system includes driving the RF modulator with a signal derived from a high stability frequency reference.
69. The apparatus of claim 66, wherein the feedback system includes monitoring the quality of the wavelengths on either side of the desired wavelength set.
70. The apparatus of claim 66, wherein the feedback system includes imposing a low frequency modulation on the high stability frequency reference.
71. The apparatus of claim 70, wherein the feedback system includes monitoring the quality of the wavelength on either side of the desired wavelength set and using the imposed low frequency modulation.
72. The apparatus of claim 71, wherein the effects of the low frequency modulation are compensated for when the generated wavelengths are modulated with data.
73. A wavelength generating means operable to generate radiation with a multiplicity of specific discrete wavelengths, the means comprising: means for positioning a multipHcity of distributed reflective elements in an optical processing element; and means for generating optical pump radiation by at least one optically active element, said optically active element optically coupled to the optical processing element, and means for transmitting such optical pump radiation to the optical processing element, such that radiation with a multipHcity of discrete wavelengths is generated.
PCT/US2002/003600 2001-02-08 2002-02-07 Self seeded multiple wavelength generation WO2002063729A9 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5323404A (en) * 1993-11-02 1994-06-21 At&T Bell Laboratories Optical fiber laser or amplifier including high reflectivity gratings
US5548433A (en) * 1992-04-27 1996-08-20 British Telecommunications Public Limited Company Optical clock recovery
US5796765A (en) * 1993-10-11 1998-08-18 British Telecommunication Public Limited Company Optical pulse seqeunce generator
US6052393A (en) * 1996-12-23 2000-04-18 The Regents Of The University Of Michigan Broadband Sagnac Raman amplifiers and cascade lasers

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5548433A (en) * 1992-04-27 1996-08-20 British Telecommunications Public Limited Company Optical clock recovery
US5796765A (en) * 1993-10-11 1998-08-18 British Telecommunication Public Limited Company Optical pulse seqeunce generator
US5323404A (en) * 1993-11-02 1994-06-21 At&T Bell Laboratories Optical fiber laser or amplifier including high reflectivity gratings
US6052393A (en) * 1996-12-23 2000-04-18 The Regents Of The University Of Michigan Broadband Sagnac Raman amplifiers and cascade lasers

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