US4474427A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical fiber reflective filter
Assignee: Canada Minister of Communications
•
Filing: 1979-05-07
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Granted: 1984-10-02
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Expires: 1999-05-07
Abstract
Abstract The optical reflective filter is made from a photosensitive optical fiber having a cladding and a core including germanium. Refractive index perturbations are light induced in the fiber in the region of the guided light. The perturbations can be made to have a constant or a varying periodicity, or a series of constant periodicities. The filters are made from single mode or low order mode fibers having germanium doped silica or germania cores. The center frequency for reflective band or bands has a wavelength in the 400 nm to 550 nm range. The reflective band or bands in the filter can be shifted by stretching the filter.
Inventors
- 👤 Kenneth O. Hill
- 👤 Brian S. Kawasaki
- 👤 Derwyn C. Johnson
- 👤 Yoshimasa Fujii
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:17
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/02; G02B6/02057; G02B6/02076; G02B6/02195; G02B6/022; G02B5/00; G02B5/20; G02B5/26; G02B6/02123; G02B6/02128; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
39 words
An optical refective filter comprising a photosensitive optical fiber having a cladding and a core including germanium and having a minimum numerical aperture of 0.1 wherein refractive index perturbations are light induced in the region of the guided light.
Claim 2
Dependent Claim
39 words
An optical refective filter comprising a photosensitive optical fiber having a cladding and a core including germanium and having a minimum numerical aperture of 0.1 wherein refractive index perturbations are light induced in the region of the guided light.
Claim 3
Dependent Claim
24 words
An optical reflective filter as claimed in claim 1 wherein the periodicity of the perturbations is substantially constant along the length of the filter.
Claim 4
Dependent Claim
22 words
An optical reflective filter as claimed in claim 1 wherein the periodicity of the perturbations varies along the length of the filter.
Claim 5
Dependent Claim
35 words
An optical reflective filter as claimed in claim 1 wherein the perturbations consist of at least two series of perturbations, each series of perturbations having a predetermined constant periodicity along the length of the filter.
Claim 6
Dependent Claim
17 words
An optical reflective filter as claimed in claim 1 wherein the core consists of germanium doped silica.
Claim 7
Dependent Claim
15 words
An optical reflective filter as claimed in claim 1 wherein the core consists of germania.
Claim 8
Dependent Claim
31 words
An optical reflective filter as claimed in claim 1 wherein the periodicity of the perturbations is such as to reflect light in the wavelength range of 400 nm to 550 nm.
Claim 9
Dependent Claim
20 words
An optical reflective filter as claimed in claim 1 which further includes means for stretching the filter along its length.
Claim 10
Dependent Claim
17 words
An optical reflective filter as claimed in claim 1 wherein the fiber is a single mode fiber.
Claim 11
Dependent Claim
17 words
An optical reflective filter as claimed in claim 1 wherein the fiber is a single mode fiber.
Claim 12
Independent Claim
71 words
A method of making an optical reflective filter from a photosensitive fiber having a cladding and a core comprising the steps of: (a) transmitting a predetermined coherent light beam through the fiber in one direction; and (b) reflecting the light beam back through the fiber in the other direction to interfere with the launched beam to form a stable interference pattern so as to produce refractive index perturbations in the fiber.
Claim 13
Independent Claim
71 words
A method of making an optical reflective filter from a photosensitive fiber having a cladding and a core comprising the steps of: (a) transmitting a predetermined coherent light beam through the fiber in one direction; and (b) reflecting the light beam back through the fiber in the other direction to interfere with the launched beam to form a stable interference pattern so as to produce refractive index perturbations in the fiber.
Claim 14
Dependent Claim
25 words
A method as claimed in claim 11 which includes the step of subjecting the fiber to a constant longitudinal tension during steps (a) and (b).
Claim 15
Dependent Claim
23 words
A method as claimed in claim 11 which includes the step of protecting the fiber from temperature fluctuations during steps (a) and (b).
Claim 16
Dependent Claim
28 words
A method as claimed in claim 13 which further includes the step of subjecting the fiber to a temperature gradient along its length during steps (a) and (b).
Claim 17
Dependent Claim
28 words
A method as claimed in claim 11 which includes the step of subjecting the fiber to a longitudinal tension gradient along its length during steps (a) and (b).
Claim 18
Dependent Claim
45 words
A method as claimed in claim 11 wherein the fiber is a low-order mode fiber with a numerical aperture greater than 0.1 and having a germanium doped silica core, and the light beam has a wavelength in the range of 400 nm to 550 nm.
Claim 19
Dependent Claim
24 words
A method as claimed in claim 11 which includes the repetition of steps (a) and (b) with one or more different coherent light beams.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-02 | 1988-04-02 | 1988-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-02 | 1992-04-02 | 1992-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-02 | 1996-04-02 | 1996-10-02 | $7700.00 | Window Closed / Lapsed |