Optical network monitor

• US 20050078957A1
• Filed: 10/18/2004
• Published: 04/14/2005
• Est. Priority Date: 06/23/1998
• Status: Active Grant

• Current Assignee: Lumentum Operations, LLC (Lumentum Holdings Inc.)
• Original Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Inventors: Hendow, Sami T.
• Granted Patent: US 7,006,765 B2
• Time in Patent Office: Days
• US Class Current: 398/33
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: H04B 10/077 using a supervisory or additional signal
• CPC Class Codes: H04B 10/07955 Monitoring or measuring power
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04Q 11/0062 Network aspects
• CPC Class Codes: H04Q 2011/0049 Crosstalk reduction; Noise; Power budget
• CPC Class Codes: H04Q 2011/0083 Testing; Monitoring

Abstract

An optical network monitor and a method for monitoring the optical signals of an optical network including a spectrograph that includes a detector array, a processor and outputs. The network monitor receives an optical input signal which includes individual channels. The optical signal is transmitted onto the spectrograph which disperses the optical signal into the individual channels. The individual channels are directed onto the detector array so that the channels are spaced across the detector array. The detector array detects the channels in parallel and transmits to the processor channel parameter data which is processes the parameter data through internal algorithms to produce the outputs.

Claims

1-60. -60. (canceled)

61. An optical network monitor for monitoring optical signals on an optical network, comprising:

a spectrograph for receiving an optical input signal including individual channels, including dispersing means for dispersing the optical signal into the individual channels, and means for reducing polarization dependent losses;

a detector array including a plurality of detector elements positioned so that the channels are spaced across the detector array, whereby the detector array detects the channels in parallel and creates a detector output signal representative of the intensity of the optical signal for each channel.

62. The optical network monitor according to claim 61, wherein the spectrograph includes first and second gratings configured to disperse the optical signal into individual channels and onto the detector array.

63. The optical network monitor according to claim 61, further comprising processing means for processing the detector output signal through internal algorithms to produce an output.

64. The optical network monitor according to claim 63, wherein the processing means includes a digital signal processor and a micro-controller for accessing memory internally or externally of the processing means.

65. The optical network monitor according to claim 63, wherein the internal algorithms include means for calibrating the output.

66. The optical network monitor according to claim 65, wherein the means for calibrating the output includes removal of dark current from an element voltage.

67. The optical network monitor according to claim 65, wherein the means for calibrating the output includes adjustment of an element voltage through a calibration table, which includes a map of element voltage and element sequence number to optical power and wavelength.

68. The optical network monitor according to claim 63, wherein the detector output signal is an element voltage sampled from at least one element of the detector array.

69. The optical network monitor according to claim 68, wherein the processing means generates an average of the element voltage by:

a) integrating the wavelengths across the detector array, b) sampling the integrated wavelengths creating the element voltage, c) converting the element voltage from analog, and d) repeat steps a) to c) at least twice and averaging the element voltage.

70. The optical network monitor according to claim 61, wherein the spectrograph further comprises:

means for collimating the input optical signal which produces a collimated signal for direction at the dispersing means, and means for focusing the dispersed channels across the detector array.

71. The optical network monitor according to claim 61, wherein the means for reducing polarization dependent losses includes a half-wave plate.

72. The optical network monitor according to claim 71, wherein the dispersing means includes a first and a second grating, wherein the means for reducing polarization dependent losses is positioned between the first grating and the second grating.

73. An optical network monitor for monitoring optical signals, comprising:

a spectrograph for receiving an optical input signal including individual wavelengths, including dispersing means for dispersing the optical signal into the individual channels, and means for reducing polarization dependent losses; and

a detector array including a plurality of detector elements positioned so that the wavelengths are spaced across the detector array, whereby the detector array detects the wavelengths in parallel and creates a detector output signal representative of the intensity of the optical signal for the individual wavelengths.

74. The optical network monitor according to claim 73, wherein the wavelengths are spaced across the detector array in such a way that each element of the detector array receives a single wavelength.

75. The optical network monitor according to claim 73, further comprising a processing means for processing the detector output signal through internal algorithms to produce an output.

76. The optical network monitor as claimed in claim 73, wherein the detector output signal includes an alarm if certain predetermined conditions are met.

77. A spectrograph for use in analyzing optical data signals, comprising:

an input for launching an optical signal;

a first lens for collimating the optical signal to produce a collimated beam;

dispersing means for dispersing the collimated beam into dispersed channels;

means for reducing polarization dependent loss positioned to receive the dispersed channels;

a linear detector array for detecting the dispersed channels in parallel and creating a detector output signal representative of the intensity of the optical signal for each channel; and

a second lens for focusing the dispersed channels across the linear detector array.

78. The spectrograph according to claim 77, wherein the dispersing means includes a first and a second grating, wherein the first lens directs the collimated beam onto the first grating to produce a dispersed beam, wherein the first grating directs the dispersed beam onto the second grating to produce the dispersed channels, wherein the second grating directs the dispersed channels onto the second lens for focusing the dispersed channels.

79. The spectrograph as claimed in claim 78, wherein the means for reducing polarization dependent losses is positioned between the first grating and the second grating, wherein the dispersed beam passes through the means for reducing polarization dependent losses before contacting the second grating.

80. The spectrograph as claimed in claim 77, wherein the means for reducing polarization dependent losses includes a half-wave plate.