US6005995A — Frequency sorter, and frequency locker for monito…

Claim 1

Independent Claim 107 words

A method for locking the frequencies of a plurality of radiation sources substantially to predetermined equally spaced frequencies spaced apart by a predetermined frequency spacing, comprising: providing one or more frequency lockers having equally spaced periodic frequencies with a free spectral range (FSR) substantially equal to the predetermined frequency spacing, wherein said periodic frequencies are close to the predetermined frequencies; passing radiation from each of the sources through the locker or one of the lockers; detecting radiation passed by the locker or one of the lockers and providing first outputs; and adjusting the frequency of each of the sources in response to one of said first outputs.

Claim 2

Independent Claim 107 words

A method for locking the frequencies of a plurality of radiation sources substantially to predetermined equally spaced frequencies spaced apart by a predetermined frequency spacing, comprising: providing one or more frequency lockers having equally spaced periodic frequencies with a free spectral range (FSR) substantially equal to the predetermined frequency spacing, wherein said periodic frequencies are close to the predetermined frequencies; passing radiation from each of the sources through the locker or one of the lockers; detecting radiation passed by the locker or one of the lockers and providing first outputs; and adjusting the frequency of each of the sources in response to one of said first outputs.

Claim 3

Dependent Claim 35 words

The method of claim 1, further comprising detecting radiation from the sources to provide second outputs, wherein the adjusting adjusts the frequency of each of the sources in response to the first and second outputs.

Claim 4

Dependent Claim 32 words

The method of claim 1, wherein the passing passes radiation of the sources sequentially, the detecting detects radiation from the sources sequentially and the adjusting adjusts the frequencies of the sources sequentially.

Claim 5

Dependent Claim 25 words

The method of claim 3, wherein the passing, detecting and adjusting are performed on the sources at a frequency of at least about 0.1 Hz.

Claim 6

Independent Claim 110 words

An apparatus for locking the frequencies of a plurality of radiation sources substantially to predetermined equally spaced frequencies spaced apart by a predetermined frequency spacing, comprising: one or more frequency lockers, the locker or each of the lockers having equally spaced periodic frequencies with a free spectral range (FSR) substantially equal to the predetermined frequency spacing, means for passing radiation from each of the sources through the locker or one of the lockers; one or more first detectors detecting radiation passed by the locker or one of the lockers to provide first outputs; and means for adjusting the frequency of each of the sources in response to said first outputs.

Claim 7

Independent Claim 110 words

An apparatus for locking the frequencies of a plurality of radiation sources substantially to predetermined equally spaced frequencies spaced apart by a predetermined frequency spacing, comprising: one or more frequency lockers, the locker or each of the lockers having equally spaced periodic frequencies with a free spectral range (FSR) substantially equal to the predetermined frequency spacing, means for passing radiation from each of the sources through the locker or one of the lockers; one or more first detectors detecting radiation passed by the locker or one of the lockers to provide first outputs; and means for adjusting the frequency of each of the sources in response to said first outputs.

Claim 8

Dependent Claim 15 words

The apparatus of claim 5, wherein said periodic frequencies are close to the predetermined frequencies.

Claim 9

Dependent Claim 41 words

The apparatus of claim 5, further comprising one or more second detectors detecting radiation from the sources to provide second outputs, wherein the adjusting means adjusts the frequency of each of the sources in response to the first and second outputs.

Claim 10

Dependent Claim 41 words

The apparatus of claim 5, said apparatus comprising only one frequency locker and further comprising a multi-channel switch supplying radiation from each of the sources sequentially to the locker so that the adjusting means adjusts the frequencies of the sources sequentially.

Claim 11

Dependent Claim 21 words

The apparatus of claim 8, wherein the multi-channel switch is operated at a scanning period of about 100 seconds or less.

Claim 12

Dependent Claim 25 words

The apparatus of claim 5, wherein the locker includes an etalon having an optical path length that is accurate to about 0.5 microns or better.

Claim 13

Dependent Claim 40 words

A frequency sorting device, comprising: an etalon having an optical path length that is accurate to about 0.5 microns or better; an input optical fiber supplying radiation to the etalon; and an output optical fiber delivering radiation from the etalon.

Claim 14

Dependent Claim 40 words

A frequency sorting device, comprising: an etalon having an optical path length that is accurate to about 0.5 microns or better; an input optical fiber supplying radiation to the etalon; and an output optical fiber delivering radiation from the etalon.

Claim 15

Dependent Claim 30 words

The device of claim 11, said etalon comprising two reflective surfaces and a spacer between the two surfaces, said spacer including two portions having different optical and/or thermal expansion characteristics.

Claim 16

Dependent Claim 33 words

The device of claim 12, one of the two portions having a positive thermal coefficient of optical thickness and the other of the two portions having a negative thermal coefficient of optical thickness.

Claim 17

Dependent Claim 35 words

The device of claim 12, one of the two portions having a positive refraction index to temperature change ratio and the other of the two portions having a negative refraction index to temperature change ratio.

Claim 18

Dependent Claim 16 words

The device of claim 12, wherein said two portions include fused silica and/or Schott FK51 glass.

Claim 19

Dependent Claim 35 words

The device of claim 12, said etalon having an optical path through the two portions, wherein each of the two portions has an optical thickness proportional to a thermal expansion coefficient of the other portion.

Claim 20

Dependent Claim 37 words

The device of claim 11, comprising two reflective surfaces and a spacer between the two surfaces, said spacer having a thickness of about 0.85 mm to 1.05 mm or an integral or fractional multiple of such range.

Claim 21

Dependent Claim 36 words

The device of claim 11, comprising two reflective surfaces and an air gap between the two surfaces, said air gap being about 1.4 mm to 1.6 mm or an integral or fractional multiple of such range.

Claim 22

Dependent Claim 39 words

The device of claim 11, comprising two reflective surfaces and substantially a vacuum between the two surfaces, said surfaces being separated by a distance within about 1.49 to 1.51 mm or an integral or fractional multiple of such range.

Claim 23

Dependent Claim 23 words

The device of claim 11, comprising two reflective surfaces and a spacer between the two surfaces, said spacer including Zerodur™ or ULE™ glass.

Claim 24

Dependent Claim 70 words

The device of claim 11, said etalon having an optical path, comprising: two reflective surfaces; two pedestals, each pedestal supporting one of the two surfaces; and one or more spacers between the two pedestals, wherein the dimensions of the spacer(s) and the pedestals along the optical path and their thermal expansion coefficients are such that temperature effects on the pedestals substantially cancel those on the spacer(s) within a temperature range.

Claim 25

Dependent Claim 16 words

The device of claim 21, said temperature range is from about -20 to 85 degrees Centigrade.

Claim 26

Dependent Claim 28 words

The device of claim 11, said optical path length being accurate to about 0.5 microns or better within a temperature range from about -20 to 85 degrees Centigrade.

Claim 27

Dependent Claim 30 words

The device of claim 11, said input fiber supplying broad band radiation to the etalon, said output fiber delivering radiation having periodic frequencies with a frequency spacing from the etalon.

Claim 28

Dependent Claim 34 words

The device of claim 11, said input fiber supplying radiation within a pass band to the etalon, said output fiber delivering radiation having a narrower band width than the pass band from the etalon.

Claim 29

Dependent Claim 21 words

The device of claim 25, further comprising a filter filtering and passing radiation within said pass band to the input fiber.

Claim 30

Dependent Claim 43 words

A frequency sorting method, comprising: providing an etalon having an optical path length that is accurate to about 0.5 microns or better; supplying broad band radiation to the etalon; and delivering from the etalon radiation having periodic peak frequencies with a frequency spacing.

Claim 31

Dependent Claim 43 words

A frequency sorting method, comprising: providing an etalon having an optical path length that is accurate to about 0.5 microns or better; supplying broad band radiation to the etalon; and delivering from the etalon radiation having periodic peak frequencies with a frequency spacing.

Claim 32

Dependent Claim 46 words

A frequency sorting method, comprising: providing an etalon having an optical path length that is accurate to about 0.5 microns or better; supplying radiation within a pass band to the etalon; and delivering radiation having a narrower band width than the pass band from the etalon.

Claim 33

Dependent Claim 46 words

A frequency sorting method, comprising: providing an etalon having an optical path length that is accurate to about 0.5 microns or better; supplying radiation within a pass band to the etalon; and delivering radiation having a narrower band width than the pass band from the etalon.

Claim 34

Dependent Claim 19 words

The device of claim 28, said supplying including filtering and passing radiation through a filter having said pass band.

Claim 35

Dependent Claim 42 words

An optical device comprising: an etalon having two reflective surfaces, said etalon having an optical path between the two surfaces having a length that is accurate to about 0.5 microns or better; and a first GRIN lens abutting one of the surfaces.

Claim 36

Dependent Claim 42 words

An optical device comprising: an etalon having two reflective surfaces, said etalon having an optical path between the two surfaces having a length that is accurate to about 0.5 microns or better; and a first GRIN lens abutting one of the surfaces.

Claim 37

Dependent Claim 18 words

The device of claim 30, further comprising a second GRIN lens abutting the other one of the surfaces.

Claim 38

Dependent Claim 28 words

The device of claim 31, said lenses being separated from the etalon by a gap, said device further comprising anti-reflection coatings on the etalon and the two lenses.

Claim 39

Dependent Claim 43 words

The device of claim 30, said first GRIN lens having an axis, said device further comprising means for supplying along a first input optical path substantially parallel to said axis, incident on the first GRIN lens and at a distance from the axis.

Claim 40

Dependent Claim 13 words

The device of claim 33, said supplying means being an input optical fiber.

Claim 41

Dependent Claim 19 words

The device of claim 34, further comprising an output optical fiber delivering a beam of radiation from the etalon.

Claim 42

Dependent Claim 15 words

The device of claim 32, further comprising an adhesive attaching the lenses to the etalon.

Claim 43

Independent Claim 81 words

A method for making an etalon, comprising: determining a desired optical path length for the etalon; providing two reflective surfaces; and adjusting the optical path length of the etalon, said adjusting including changing a distance between the surfaces or altering an angle of incidence of a beam of radiation on said surfaces so that an optical distance through an optical medium between the surfaces is substantially equal to the desired optical path length, said changing including thin film deposition or etching.

Claim 44

Independent Claim 81 words

A method for making an etalon, comprising: determining a desired optical path length for the etalon; providing two reflective surfaces; and adjusting the optical path length of the etalon, said adjusting including changing a distance between the surfaces or altering an angle of incidence of a beam of radiation on said surfaces so that an optical distance through an optical medium between the surfaces is substantially equal to the desired optical path length, said changing including thin film deposition or etching.

Claim 45

Dependent Claim 79 words

The method of claim 37, said altering including: passing said beam through a first GRIN lens having an axis along a first input optical path substantially parallel to said axis incident on the first GRIN lens and at a distance from the axis; and selecting said distance so that, after passing the lens, said beam impinges the etalon at such an angle that the optical path length of the etalon is substantially equal to the desired optical path length.

Claim 46

Dependent Claim 22 words

The method of claim 38, said altering further comprising passing a beam of radiation from the etalon through a second GRIN lens.

Claim 47

Dependent Claim 140 words

A multiplexer system comprising: a plurality of radiation sources providing radiation at predetermined equally spaced frequencies spaced apart by a predetermined frequency spacing; a plurality of optical channels, each channel conveying radiation from a corresponding source to a wavelength division multiplexer or from a wavelength division demultiplexer; a frequency locker having equally spaced periodic frequencies with a free spectral range (FSR) substantially equal to the predetermined frequency spacing for detecting a frequency shift of radiation from each of the sources and to provide an output; splitters, each splitter diverting a percentage of radiation from a corresponding optical channel; a multi-channel switch sequentially providing radiation diverted by one of the splitters to the frequency locker to sequentially detect a frequency shift in the plurality of sources; and means for adjusting frequencies of the plurality of sources in response to the output.

Claim 48

Dependent Claim 140 words

A multiplexer system comprising: a plurality of radiation sources providing radiation at predetermined equally spaced frequencies spaced apart by a predetermined frequency spacing; a plurality of optical channels, each channel conveying radiation from a corresponding source to a wavelength division multiplexer or from a wavelength division demultiplexer; a frequency locker having equally spaced periodic frequencies with a free spectral range (FSR) substantially equal to the predetermined frequency spacing for detecting a frequency shift of radiation from each of the sources and to provide an output; splitters, each splitter diverting a percentage of radiation from a corresponding optical channel; a multi-channel switch sequentially providing radiation diverted by one of the splitters to the frequency locker to sequentially detect a frequency shift in the plurality of sources; and means for adjusting frequencies of the plurality of sources in response to the output.

Claim 49

Independent Claim 56 words

A method for locking the frequencies of a plurality of radiation sources to International Telecommunication Union (ITU) frequencies, comprising: measuring a frequency shift of said sources relative to said ITU frequencies; and adjusting the frequencies of said radiation sources in response to said frequency shift so that such frequencies are substantially equal to said ITU frequencies.

Claim 50

Independent Claim 56 words

A method for locking the frequencies of a plurality of radiation sources to International Telecommunication Union (ITU) frequencies, comprising: measuring a frequency shift of said sources relative to said ITU frequencies; and adjusting the frequencies of said radiation sources in response to said frequency shift so that such frequencies are substantially equal to said ITU frequencies.

Claim 51

Dependent Claim 24 words

The method of claim 40, wherein the frequencies of said radiation sources are adjusted to be within about 5 GHz of said ITU frequencies.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2002-12-20	2003-06-21	2003-12-21	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2006-12-20	2007-06-21	2007-12-21	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2010-12-20	2011-06-21	2011-12-21	$7700.00	Window Closed / Lapsed

Frequency sorter, and frequency locker for monitoring frequency shift of radiation source

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