US3900247A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical modulator having compensation for thermal and space charge effects
Assignee: Nortel Networks Ltd
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Filing: 1974-02-26
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Granted: 1975-08-19
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Expires: 1994-02-26
Abstract
Abstract An optical modulator in which a polarized light beam is reflected back through its optical modulation element after a 180* relative phase shift between the ordinary and extraordinary components of the beam, so as to nullify any modulation caused by thermal or space charge effects. To obtain modulation, the birefringence of the modulation element is changed during the finite transmission time of the modulator. Thus only the dynamic birefringence of the element causes modulation and not its static value.
Inventors
- 👤 Safwat George Zaky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:25
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/03
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
165 words
In an optical modulator for connection to a source of linearly polarized light, comprising in tandem connected optical combination; a beam splitter for splitting the linearly polarized light which is reentrant from that which is incident thereupon; a mirror; and a variable birefringent device located between the beam splitter and the mirror; the improvement comprising: a quarter-wave plate located between the variable birefringent device and the mirror; the optical axis of the birefringent device being at an angle of pi /4 radians with respect to that of the source of linearly polarized light and the quarter-wave plate, and the total optical transmission time from the Variable birefringent device through the quarter-wave plate to the mirror and back again being at least as great as the time required to change the birefringence of said device; whereby the relative phase shift, of the ordinary and extraordinary components of the polarized light in said modulator is substantially a result of only said change in birefringence of said device.
Claim 2
Dependent Claim
165 words
In an optical modulator for connection to a source of linearly polarized light, comprising in tandem connected optical combination; a beam splitter for splitting the linearly polarized light which is reentrant from that which is incident thereupon; a mirror; and a variable birefringent device located between the beam splitter and the mirror; the improvement comprising: a quarter-wave plate located between the variable birefringent device and the mirror; the optical axis of the birefringent device being at an angle of pi /4 radians with respect to that of the source of linearly polarized light and the quarter-wave plate, and the total optical transmission time from the Variable birefringent device through the quarter-wave plate to the mirror and back again being at least as great as the time required to change the birefringence of said device; whereby the relative phase shift, of the ordinary and extraordinary components of the polarized light in said modulator is substantially a result of only said change in birefringence of said device.
Claim 3
Dependent Claim
71 words
An optical modulator as defined in claim 1 in which the variable birefringent device is an electro-optic crystal, and in which the beam splitter is a polarization separator having its incident optical axis parallel to that of said source, so that only the component of the reentrant light which is orthogonal to the incident light emerges at its output, thereby providing amplitude modulated light at the output of the optical modulator.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-18 | 1979-02-17 | 1979-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-18 | 1983-02-17 | 1983-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-18 | 1987-02-17 | 1987-08-19 | $7700.00 | Window Closed / Lapsed |