FLAT TOP TUNABLE FILTER WITH INTEGRATED DETECTOR
A free space tunable filter produces a passband output as a result of sequential processing by an array of narrowband tunable filters (NBTFs) each tuned to a slIghtly different frequency. The present invention is comprised of one or more stages having multiple interleaved sectors and comprising an array of NBTFs having a masked outer surface reflective coating. Stages cascading is used to increase the device figure of merit and single stages are partitioned into multiple sectors that process a specific interleaved region of the bandwidth. Final stage output group passband signals are combined in a multiplexer and tapped with a partially transparent photodetector.
1 . A tunable optical filter comprising a narrowband tunable filter array deposited on an inside surface of a first and second substrate, and, a reflective coating deposited on an outer surface of each substrate.
2 . The tunable optical filter of claim 1 , further comprising a patterned hole in at least one reflective surface to allow a light signal to pass.
3 . The tunable optical filter of claim 1 , wherein the narrowband tunable filter is a liquid crystal device.
4 . The tunable optical filter of claim 1 , further including a quarter wave reflective rotator on an outer surface of at least one of the substrates.
5 . The tunable optical filter of claim 1 , wherein the narrowband tunable filters are bi-directional devices that pass a transmission band and reflect a passband.
6 . The tunable optical filter of claim 1 , wherein each narrowband tunable filter further is individually controlled by an application of voltage to an electrode layer associated therewith.
7 . The tunable optical filter of claim 1 , wherein the narrowband tunable filters are configured with slightly different center wavelength resonant frequencies.
8 . The tunable optical filter of claim 2 , wherein at least one hole is positioned at the input of the device.
9 . The tunable optical filter of claim 2 , wherein at least one hole is positioned at the output of the device.
10 . The tunable optical filter of claim 7 , wherein the narrowband tunable filter array further including a common electrode layer.
11 . The tunable optical filter of claim 10 wherein the device is tuned by an application of voltage to the common electrode layer.
12 . A tunable optical filter comprising N stages, each stage comprising a narrowband tunable filter array deposited on an inside surface of substantially parallel first and second substrate each of which first and second substrates having a reflective coating deposited on an outer surface.
13 . The tunable optical filter of claim 12 , wherein the pixels are aligned in a single row or column along the length of the substrate.
14 . The tunable optical filter of claim 12 , wherein the pixels are aligned in a single row and column along the length and width of the substrate.
15 . The tunable optical filter of claim 12 , wherein an optical signal input to the filter will be split into a transmission band and a passband signal.
16 . The tunable optical filter of claim 13 , wherein each stage further includes holes which allows a group passband signal to enter and exit.
17 . The tunable optical filter of claim 13 , wherein at least one stage has associated therewith array members of the narrowband tunable filter grouped into sectors.
18 . The tunable optical filter of claim 17 , wherein each sector associated with said stage produces a group passband output.
19 . The tunable optical filter of claim 18 , wherein at least one of said sectors produces a group transmission output which couples to an input of another of said sectors.
20 . The tunable optical filter of claim 19 , further including a MUX for combining group passband signals.
21 . The tunable optical filter of claim 20 , wherein the MUX includes an integrated photodetector tap.
22 . A tunable optical filter comprising,
a narrowband tunable filter array deposited on an inside surface of a first and second substrate, and a reflective coating deposited on an outer surface of each substrate, and,
a temperature compensation means for controlling the tunable optical filter.