Spectral filter having controllable spectral bandwidth and resolution
First Claim
1. An apparatus comprising a spectral filter that is operative for receiving a first light signal characterized by a first spectral range and providing a second light signal that is spectrally dispersed along a first direction, wherein the second light signal is characterized by a second spectral range within the first spectral range, and wherein the spectral filter includes:
- a first mirror that is planar and partially transmissive for the first light signal;
a second mirror that is planar and partially transmissive for the first light signal, wherein the first mirror and second mirror define an optically resonant cavity having a cavity length that is controllable along the first direction; and
a first actuator that is configured to control a first separation between the first mirror and second mirror at a first location, wherein a first angle of the first mirror relative to the second mirror along the first direction is based on the first separation;
wherein the second spectral range has a first spectral width that is based on the first angle; and
wherein the spectral filter is configured such that, when the first light signal propagates along a second direction and the spectral filter is in its quiescent state, each of the first mirror and second mirror is oriented at a second angle relative to the second direction, and wherein the second angle is not equal to 90°
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Abstract
A Fabry-Perot cavity-based spectral notch filter is disclosed, where the filter is operative for providing an output optical signal whose spectral content is spatially dispersed along at least one direction, while also controlling the spectral position and spectral range of the output light. In some embodiments, the spectral filter is integrated with a detector arrays to realize a compact, high-resolution spectrometer that can rapidly acquire the absorption spectrum of a sample with high sensitivity.
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Citations
28 Claims
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1. An apparatus comprising a spectral filter that is operative for receiving a first light signal characterized by a first spectral range and providing a second light signal that is spectrally dispersed along a first direction, wherein the second light signal is characterized by a second spectral range within the first spectral range, and wherein the spectral filter includes:
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a first mirror that is planar and partially transmissive for the first light signal; a second mirror that is planar and partially transmissive for the first light signal, wherein the first mirror and second mirror define an optically resonant cavity having a cavity length that is controllable along the first direction; and a first actuator that is configured to control a first separation between the first mirror and second mirror at a first location, wherein a first angle of the first mirror relative to the second mirror along the first direction is based on the first separation; wherein the second spectral range has a first spectral width that is based on the first angle; and wherein the spectral filter is configured such that, when the first light signal propagates along a second direction and the spectral filter is in its quiescent state, each of the first mirror and second mirror is oriented at a second angle relative to the second direction, and wherein the second angle is not equal to 90°
. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus comprising a spectral filter that is operative for receiving a first light signal characterized by a first spectral range and providing a second light signal that is spectrally dispersed along a first direction, wherein the second light signal is characterized by a second spectral range within the first spectral range, and wherein the spectral filter includes:
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a first mirror that is planar and partially reflective for the first light signal; a second mirror that is planar and partially reflective for the first light signal, wherein the second mirror is moveable with respect to the first mirror, and wherein the second mirror is parallel with the first mirror when the spectral filter is in its quiescent state; and a first actuator that is configured to control a first angle between the first mirror and the second mirror along a first direction, wherein the second spectral range has a first spectral width that is based on the first angle; wherein the spectral filter is configured such that, when the first light signal propagates along a second direction and the spectral filter is in its quiescent state, each of the first mirror and second mirror is oriented at a second angle relative to the second direction, and wherein the second angle is not equal to 90°
. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method comprising:
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(1) receiving a first light signal at a spectral filter that is characterized by a first spectral range, wherein the spectral filter includes; (i) a first mirror that is planar and partially transmissive for the first light signal; and (ii) a second mirror that is planar and partially transmissive for the first light signal, wherein the second mirror has a first angle relative to the first mirror along a first direction, and wherein the first angle is controllable; wherein the first and second mirror define an optically resonant cavity having a cavity length that is a first linear function of position along the first direction; wherein the first light signal is received along a second direction, and wherein, when the spectral filter is in its quiescent state, each of the first and second mirrors is oriented at a second angle relative to the second direction, and further wherein the second angle is not equal to 90°
;(2) controlling the first angle such that it has a first magnitude; and (3) providing a second light signal from the spectral filter such that it is spectrally dispersed along the first direction, the second light signal being characterized by a second spectral range that is within the first spectral range, the second spectral range having a first spectral width that is based on the first magnitude. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification