US4190811A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser controlled optical switching in semiconductors
Assignee: National Research Council Canada
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Filing: 1977-11-11
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Granted: 1980-02-26
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Expires: 1997-11-11
Abstract
Abstract A method and apparatus for switching an infrared radiation signal laser beam in which a semiconductor, capable of transmitting the signal beam without damage, is provided and upon which the signal beam is incident at an angle which may preferably be Brewster's angle. The surface of the semiconductor is irradiated by a second laser beam which has a sufficiently high frequency to produce free carriers in the semiconductor and which has a sufficient radiation intensity and time duration to produce a free carrier density greater than the critical density for the signal beam resulting in substantially total reflection of the signal beam from the semiconductor surface. In particular, a pulsed CO 2 laser beam which is incident on a polycrystalline n-type germanium semiconductor is reflected by irradiating the semiconductor with a pulsed ruby or Nd:glass laser beam.
Inventors
- 👤 A. John Alcock
- 👤 Paul B. Corkum
- 👤 Douglas J. James
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:21
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/29; G02F1/293; G02F1/01; G02F1/015; G02F1/0126
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
128 words
An apparatus for switching a signal laser beam having a predetermined infrared radiation frequency comprising: semiconductor means normally transparent to infrared radiation of the signal beam frequency; signal laser means for providing the infrared radiation signal beam and for directing said signal beam obliquely at a predetermined angle onto the surface of said semiconductor means; and control laser means for providing a control beam for irradiating the surface of said semiconductor means, said control laser means beam having a radiation frequency sufficiently high to produce free carriers in said semiconductor means and having sufficient radiation intensity and time duration to produce a free carrier density greater than the critical density for the signal beam resulting in substantially complete reflection of the signal beam from said semiconductor means surface.
Claim 2
Independent Claim
128 words
An apparatus for switching a signal laser beam having a predetermined infrared radiation frequency comprising: semiconductor means normally transparent to infrared radiation of the signal beam frequency; signal laser means for providing the infrared radiation signal beam and for directing said signal beam obliquely at a predetermined angle onto the surface of said semiconductor means; and control laser means for providing a control beam for irradiating the surface of said semiconductor means, said control laser means beam having a radiation frequency sufficiently high to produce free carriers in said semiconductor means and having sufficient radiation intensity and time duration to produce a free carrier density greater than the critical density for the signal beam resulting in substantially complete reflection of the signal beam from said semiconductor means surface.
Claim 3
Dependent Claim
29 words
An apparatus as claimed in claim 1 wherein said signal laser means includes means for directing said signal beam onto the surface of said semiconductor means at Brewster's angle.
Claim 4
Dependent Claim
19 words
An apparatus as claimed in claim 2 wherein said signal laser means provides a plane-polarized infrared radiation signal beam.
Claim 5
Dependent Claim
45 words
An apparatus as claimed in claim 1 wherein said signal laser means provides a pulsed signal beam and said control laser means provides a pulsed control beam, and the apparatus further includes triggering means for synchronizing said signal laser means and said control laser means.
Claim 6
Dependent Claim
24 words
An apparatus as claimed in claim 4 wherein said control laser means provides a pulsed control beam having a duration smaller than 3 nanoseconds.
Claim 7
Dependent Claim
25 words
An apparatus as claimed in claim 1 wherein said signal laser means provides a radiation intensity greater than 1 MW/cm 2 at the semiconductor surface.
Claim 8
Dependent Claim
36 words
An apparatus as claimed in claim 1 wherein said signal laser means is a CO 2 laser, said control laser means is a ruby laser and said semiconductor means is a polished polycrystalline n-type germanium semiconductor.
Claim 9
Dependent Claim
37 words
An apparatus as claimed in claim 1 wherein said signal laser means is a CO 2 laser, said control laser means is a neodymium glass laser and said semiconductor means is a polished polycrystalline n-type germanium semiconductor.
Claim 10
Independent Claim
105 words
An apparatus for switching a signal laser beam having a predetermined infrared radiation frequency comprising: semiconductor means normally transparent to said infrared radiation signal laser beam; means for directing the infrared radiation signal beam obliquely onto the surface of said semiconductor means; and control laser means for providing a control beam for irradiating the surface of said semiconductor means, said control laser means beam having a radiation frequency sufficiently high to produce free carriers in said semiconductor means and having sufficient radiation intensity and time duration to produce a free carrier density resulting in substantially complete reflection of the signal beam from said semiconductor surface.
Claim 11
Independent Claim
105 words
An apparatus for switching a signal laser beam having a predetermined infrared radiation frequency comprising: semiconductor means normally transparent to said infrared radiation signal laser beam; means for directing the infrared radiation signal beam obliquely onto the surface of said semiconductor means; and control laser means for providing a control beam for irradiating the surface of said semiconductor means, said control laser means beam having a radiation frequency sufficiently high to produce free carriers in said semiconductor means and having sufficient radiation intensity and time duration to produce a free carrier density resulting in substantially complete reflection of the signal beam from said semiconductor surface.
Claim 12
Dependent Claim
16 words
Apparatus as claimed in claim 9 wherein said control laser means provides a pulsed control beam.
Claim 13
Dependent Claim
23 words
Apparatus as claimed in claim 10 wherein said control laser means provides a pulsed control beam having a duration smaller than 3 nanoseconds.
Claim 14
Dependent Claim
26 words
Apparatus as claimed in claim 9 wherein the signal beam directing means directs the signal beam onto the surface of said semiconductor means at Brewster's angle.
Claim 15
Dependent Claim
27 words
An apparatus as claimed in claim 9 wherein said control laser means is a ruby laser and said semiconductor means is a polished polycrystalline n-type germanium semiconductor.
Claim 16
Dependent Claim
28 words
An apparatus as claimed in claim 9 wherein said control laser means is a neodymium glass laser and said semiconductor means is a polished polycrystalline n-type germanium semiconductor.
Claim 17
Independent Claim
99 words
A method of switching a signal laser beam having a predetermined infrared radiation frequency comprising: directing the infrared radiation signal laser beam obliquely at a predetermined angle onto the surface of a semiconductor normally transparent to said signal laser beam; and irradiating the semiconductor surface with a control laser beam having a radiation frequency sufficiently high to produce free carriers in said semiconductor and having sufficient radiation intensity and time duration to produce a free carrier density greater than the critical density for the signal beam for producing substantially complete reflection of the signal beam from said semiconductor surface.
Claim 18
Independent Claim
99 words
A method of switching a signal laser beam having a predetermined infrared radiation frequency comprising: directing the infrared radiation signal laser beam obliquely at a predetermined angle onto the surface of a semiconductor normally transparent to said signal laser beam; and irradiating the semiconductor surface with a control laser beam having a radiation frequency sufficiently high to produce free carriers in said semiconductor and having sufficient radiation intensity and time duration to produce a free carrier density greater than the critical density for the signal beam for producing substantially complete reflection of the signal beam from said semiconductor surface.
Claim 19
Dependent Claim
24 words
A method as claimed in claim 15 which further includes the step of: controlling the control laser to provide a pulsed control laser beam.
Claim 20
Dependent Claim
30 words
A method as claimed in claim 16 which further includes the step of: controlling the control laser to provide a pulsed control beam having a duration smaller than 3 nanoseconds.
Claim 21
Dependent Claim
30 words
A method as claimed in claim 15 which further includes the steps of: plane polarizing the signal beam; and directing the signal beam onto the semiconductor surface at Brewster's angle.
References Cited (Backward Citations)
US3555455A
Cited
US4003631A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-02-25 | 1983-08-27 | 1984-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-02-25 | 1987-08-27 | 1988-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-02-25 | 1991-08-27 | 1992-02-26 | $7700.00 | Window Closed / Lapsed |