WO2003024011A2 - Optical performance monitor - Google Patents
Optical performance monitor Download PDFInfo
- Publication number
- WO2003024011A2 WO2003024011A2 PCT/CA2002/001385 CA0201385W WO03024011A2 WO 2003024011 A2 WO2003024011 A2 WO 2003024011A2 CA 0201385 W CA0201385 W CA 0201385W WO 03024011 A2 WO03024011 A2 WO 03024011A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- wavelengths
- demultiplexed
- output waveguides
- divided output
- echelle grating
- Prior art date
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 claims description 12
- 238000012544 monitoring process Methods 0.000 claims description 7
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 claims description 4
- 230000005855 radiation Effects 0.000 claims 3
- 230000008878 coupling Effects 0.000 claims 1
- 238000010168 coupling process Methods 0.000 claims 1
- 238000005859 coupling reaction Methods 0.000 claims 1
- 238000012545 processing Methods 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 239000000969 carrier Substances 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000001429 visible spectrum Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0795—Performance monitoring; Measurement of transmission parameters
- H04B10/07955—Monitoring or measuring power
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0256—Compact construction
- G01J3/0259—Monolithic
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0286—Constructional arrangements for compensating for fluctuations caused by temperature, humidity or pressure, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a spectrometer, e.g. vacuum
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/12—Generating the spectrum; Monochromators
- G01J3/18—Generating the spectrum; Monochromators using diffraction elements, e.g. grating
- G01J3/1809—Echelle gratings
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
- G02B6/29316—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide
- G02B6/29325—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide of the slab or planar or plate like form, i.e. confinement in a single transverse dimension only
- G02B6/29326—Diffractive elements having focusing properties, e.g. curved gratings
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
- G02B6/29316—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide
- G02B6/29325—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide of the slab or planar or plate like form, i.e. confinement in a single transverse dimension only
- G02B6/29328—Diffractive elements operating in reflection
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
- G02B6/4215—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional signal
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
Definitions
- This invention relates to the field of photonics, and in particular to a monitor for monitoring the performance of photonic devices in an optical network, such as demultiplexers employed in wavelength division multiplexing.
- the monitor can, for example, accurately measure the power, wavelength, and ONSR (Optical Signal-to-Noise Ratio) for each channel.
- ONSR Optical Signal-to-Noise Ratio
- Telecommunications carriers have a need to monitor the performance of optical transport networks. For example, light will often undergo a slight wavelength shift as the light source (typically a semiconductor laser) ages and starts to fail. The telecommunications carriers need to be able to monitor this.
- a number of manufacturers offer monitoring devices, but none is capable of effectively monitoring channel power, wavelength, and OSNR, and yet at the same time have a small footprint without moving parts and be scaleable to handle a large number of channels.
- Prior art devices also have limited channel capacity.
- Kymata Ltd. offers a DWDM Power Monitor that is suitable for active monitoring of optical power levels within a DWDM system.
- this device which uses AWG (Arrayed Waveguide Grating) technology is not capable of monitoring wavelength or OSNR and is limited to 40 channels.
- AWG Arrayed Waveguide Grating
- an optical performance monitor for measuring the performance of optical networks, comprising a demultiplexer for demultiplexing an input beam into a plurality of wavelengths; an array of divided output waveguides, each divided output waveguide positioned to receive a corresponding demultiplexed wavelength from said demultiplexer, and each divided output waveguide laterally separating said corresponding demultiplexed wavelength into a first portion and a second portion; and a detector array having sensor elements positioned to receive said respective first and second portions of said demultiplexed wavelengths.
- the demultiplexer is preferably an echelle grating, such as a planar waveguide planar echelle grating, but it could be another type of demultiplexing device, such as an arrayed waveguide grating, for example. It will be understood that the expression “echelle grating” extends to any "staircase” type grating with staggered facets, including echelon gratings.
- the input beam is typically a light beam generated by a laser. It will of course be understood by one skilled in the art that the term "light” in this specification is not limited to light in the visible spectrum.
- the demultiplexed wavelengths onto the divided waveguides enables the monitor to be made very sensitive to drift. If the demultiplexed wavelengths have their nominal values, they would typically fall onto the mid-point of the divided output waveguides so that each wavelength would be split evenly into the two portions. In the event of drift, the light is no longer split evenly, and by measuring the difference between the outputs of the elements associated with the two portions, very small changes in wavelength can be detected.
- the echelle grating is preferably a blazed Rowland grating which focuses the demultiplexed wavelengths onto the divided output waveguides.
- the output waveguides are preferably ridge waveguides formed by lithography on a substrate also providing a slab waveguide to couple said output waveguides to said echelle grating.
- the optical performance monitor can typically measure power, wavelength and OSNR for each channel of an 80 channel system with 50GHz spacing. Other examples would be 40 channels at 100GHz spacing, and 160 channels at 25 GHz spacing.
- the invention provides an optical channel monitor comprising a demultiplexer for receiving a beam of incoming light and demultiplexing said coming light into a plurality of wavelengths; an array of output waveguides, each output waveguide positioned to received a corresponding demultiplexed wavelength from said demultiplexer; and a detector array having sensor elements positioned to receive said respective demultiplexed wavelengths. While sensitive to drift, such a channel monitor is suitable for measuring the power in the WDM channels, and has considerable advantages over the prior art, particularly with regard to scalability.
- the invention also provides a method of monitoring the performance of an optical network, comprising the steps of demultiplexing an input beam into a plurality of wavelengths; receiving said demultiplexed wavelengths in divided output waveguides, said output waveguides separating said demultiplexed wavelengths into laterally spaced portions; and detecting the relative intensity of said laterally spaced portions to determine the drift of said demultiplexed wavelengths from nominal values
- Figure 1 is a block diagram of an optical performance monitor
- Figure 2 is a schematic plan view of the spectrometer demultiplexer
- Figures 3A and 3B are plan views of the spectrometer demultiplexer showing the constructional details.
- the exemplary optical performance monitor shown in Figure 1 comprises a monolithic spectrometer 10, which will be described in more detail below, an InGaAs array detector 11, a sweep circuit 12, and a signal processing circuit 13.
- the signal processing circuit 16 has serial and parallel data outputs.
- a temperature sensor 14 monitors the temperature of the device, and a constant temperature at a nominal value is maintained with the aid of thermoelectric cooler 15.
- the spectrometer 10 is shown in more detail in Figure 2. This is a monolithic device formed on a glass substrate having etched therein a Rowland circle blazed echelle grating 21.
- a Rowland grating is described, for example, in the article Planar Rowland Spectrometer for fiber-optic Wavelength Demultiplexing, H.W.Yen, H.R. Friedrich, R.J. Morrison, and G.L.Tangonan, December 1981, Vol. 6, No. 12, Optics Letters.
- the echelle grating receives a multiplexed input beam containing a number of wavelengths ( ⁇ j , ⁇ 2/ ... ⁇ n ) representing channels in a wavelength division multiplexed optical network.
- ⁇ j wavelengths
- ⁇ 2/ ... ⁇ n channels in a wavelength division multiplexed optical network.
- the echelle grating 21 demultiplexes the incoming beam and focuses the demultiplexed wavelengths ( ⁇ lr ⁇ ... ⁇ n ) onto an array of output waveguides 23.
- the output of the echelle grating 21 is coupled through a slab waveguide 22 formed in glass substrate 20.
- the output waveguides 23 are ridge waveguides formed by etching and lithographic techniques on the substrate 20. Alternate output waveguides 23', 23" are evenly divided into first and second split waveguide sections 23a and 23b. The alternate output divided waveguides 23', 23" are separated by regular undivided waveguides 23.
- the output waveguides 23 lead to an InGaAs array detector 24 having individual sensor elements 25 receiving light from each undivided waveguide and split waveguide section.
- the waveguide array When components in the input beam have their nominal wavelengths ( ⁇ -,, ⁇ ... ⁇ , centered on the ITU grid of the telecom window, the waveguide array is positioned so that they are focused onto the midpoint of the divided waveguides.
- wavelength ⁇ ⁇ is focused onto the midpoint 26 of divided waveguide 23" adjacent the leading edge 29a of waveguide divider 29.
- the light is divided equally into first and second portions passing respectively through split waveguide sections 23a, 23b, and thus impacts the corresponds sensor elements 25a, 25b with equal intensity. This is shown by the 55:50 intensity ratio picked up by sensor elements 25a, 25b. It will of course be realized that it is not necessary for the nominal wavelength to be split 50:50 as long as the monitor is properly calibrated so that the ratio for the components in each section for each nominal wavelength is known.
- wavelength ⁇ this is- assumed to have drifted slightly during its propagation through the optical network, so that the actual wavelength is now ⁇ 2 + ⁇ .
- the demultiplexed wavelength will no longer be centered on the output waveguide 23' but will be slightly offset by an amount that depends on the drift ⁇ .
- the drift is such that the light is split into the two sections in a ratio 80:20.
- the monitor can be made extremely sensitive to very small amounts of drift ⁇ .
- the monitor can of course measure the drift on a per- channel basis.
- the intermediate sensors receive light from the intervening undivided waveguides 23. These are located at positions where they do not receive a pre- assigned ITU wavelength demultiplexed by the echelle grating 21 so the only signal generated by the sensors 25c comes from background noise 28.
- the monitor can measure the optical signal-to-noise ratio (OSNR) of the optical network.
- OSNR optical signal-to-noise ratio
- the divided waveguides can be omitted and replaced by undivided waveguides.
- the monitor is no longer able to measure wavelength drift, but it can still measure channel power and OSNR.
- the use of the echelle grating 21 is desirable because it makes the monitor easily scaleable using monolithic technology.
- AWG systems could also be used for coarser systems.
- the described monitor can conveniently use a 256-channel InAsGa array. 160 sensor elements are required for the 80 channels, two for each waveguide, and 79 elements are required for insertion between the divided waveguides (This leaves 17 unused sensor elements). This is a considerable advantage when it is recognized that the cost of a 512-element array required by most prior art systems is about four times the cost of a 256-element array.
- Signal processing is simplified since the wavelength of each channel is measured optically instead of electrically.
- Signal processing can be carried out using conventional DSP (Digital Signal Processing) techniques.
- DSP Digital Signal Processing
- the use of an echelle grating gives much better resolution than was previously thought possible.
- the module can also be made smaller.
- Figures 3A and 3B show the method of construction of the spectrometer for the performance monitor.
- the echelle grating 21 and output waveguide array are formed monolithically on the glass substrate 20 by etching and lithographic techniques.
- the echelle grating 21 is associated with a prism compensator region 30 as described in our co-pending application entitled Method for Polarization Birefringence Compensation in a Waveguide Demultiplexer using a Compensator with a High Refractive Index Capping Layer", the contents of which are herein incorporated by reference.
- the input beam is directed at the echelle grating 21 by input waveguide 27 formed as ridge waveguide on substrate 20.
- Figure 3B shows a 12-wafer die.
- the optical performance monitor is capable of remote monitoring of power, wavelength, and OSNR for up to 80 channels and offers on-board signal processing. It is remotely upgradeable and can be made to be of very small size. It incorporates a high resolution demultiplexer, full detector array and signal processor.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Engineering & Computer Science (AREA)
- Optics & Photonics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Electromagnetism (AREA)
- Optical Integrated Circuits (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
Description
Claims
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA2,357,226 | 2001-09-12 | ||
CA002357226A CA2357226A1 (en) | 2001-09-12 | 2001-09-12 | Optical performance monitor |
US09/986,479 | 2001-11-08 | ||
US09/986,479 US7272276B2 (en) | 2001-09-12 | 2001-11-08 | Optical performance monitor |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2003024011A2 true WO2003024011A2 (en) | 2003-03-20 |
WO2003024011A3 WO2003024011A3 (en) | 2003-12-11 |
Family
ID=25682720
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/CA2002/001385 WO2003024011A2 (en) | 2001-09-12 | 2002-09-12 | Optical performance monitor |
Country Status (1)
Country | Link |
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WO (1) | WO2003024011A2 (en) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4430572A (en) * | 1980-09-12 | 1984-02-07 | Lignes Telegraphiques Et Telephoniques | Device for separating two light signals emitted by sources having different wavelengths and transmitted in a single optical fiber |
WO1992011516A1 (en) * | 1990-12-21 | 1992-07-09 | Unicam Limited | Spectrometer |
EP0703679A2 (en) * | 1994-09-26 | 1996-03-27 | Nippon Telegraph And Telephone Corporation | A multiwavelength simultaneous monitoring circuit employing arrayed-waveguide grating |
FR2764376A1 (en) * | 1997-06-04 | 1998-12-11 | Commissariat Energie Atomique | INTEGRATED DEVICE FOR READING SPECTRAL RAYS CONTAINED IN AN OPTICAL SPECTRUM |
WO2001018577A1 (en) * | 1999-09-03 | 2001-03-15 | Zolo Technologies, Inc. | Dense wavelength division multiplexer/demultiplexer based on echelle grating |
-
2002
- 2002-09-12 WO PCT/CA2002/001385 patent/WO2003024011A2/en not_active Application Discontinuation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4430572A (en) * | 1980-09-12 | 1984-02-07 | Lignes Telegraphiques Et Telephoniques | Device for separating two light signals emitted by sources having different wavelengths and transmitted in a single optical fiber |
WO1992011516A1 (en) * | 1990-12-21 | 1992-07-09 | Unicam Limited | Spectrometer |
EP0703679A2 (en) * | 1994-09-26 | 1996-03-27 | Nippon Telegraph And Telephone Corporation | A multiwavelength simultaneous monitoring circuit employing arrayed-waveguide grating |
FR2764376A1 (en) * | 1997-06-04 | 1998-12-11 | Commissariat Energie Atomique | INTEGRATED DEVICE FOR READING SPECTRAL RAYS CONTAINED IN AN OPTICAL SPECTRUM |
WO2001018577A1 (en) * | 1999-09-03 | 2001-03-15 | Zolo Technologies, Inc. | Dense wavelength division multiplexer/demultiplexer based on echelle grating |
Non-Patent Citations (2)
Title |
---|
POGUNTKE K R ET AL: "High-performance InP reflection-grating wavelength multiplexer" ELECTRONICS LETTERS, IEE STEVENAGE, GB, vol. 30, no. 6, 17 March 1994 (1994-03-17), pages 512-513, XP006000334 ISSN: 0013-5194 * |
TESHIMA M ET AL: "Multiwavelength simultaneous monitoring circuit employing wavelength crossover properties of arrayed-waveguide grating" ELECTRONICS LETTERS, IEE STEVENAGE, GB, vol. 31, no. 18, 31 August 1995 (1995-08-31), pages 1595-1597, XP006003319 ISSN: 0013-5194 * |
Also Published As
Publication number | Publication date |
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WO2003024011A3 (en) | 2003-12-11 |
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