Patent US4081670A successfully refreshed from Google Patents.
US4081670A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic bias control circuit for injection lasers
Assignee: AT&T Inc
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Filing: 1976-11-08
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Granted: 1978-03-28
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Expires: 1996-11-08
Abstract
Abstract An injection laser is automatically stabilized so that the laser operates above threshold when the laser current is modulated. The invention makes use of the fact that the laser junction voltage saturates at currents above the threshold. A signal which modulates the laser current and causes the laser current to fall below the threshold level therefore results in a change in the junction voltage. These changes in the junction voltage are monitored and used to increase the bias current so that the laser operates above threshold.
Inventors
- 👤 Andres Albanese
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:07
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/50; H04B10/501; H04B10/503; H04B10/504; H01; H01S; H01S5/00; H01S5/06; H01S5/062; H01S5/06209; H01S5/06213; H01S5/068; H01S5/06808; H01S5/06812; H01S5/0683; H01S5/06832
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
75 words
An automatic bias control circuit for an injection laser which laser current is modulated in response to a modulating signal comprising: means for deriving an error voltage directly from changes in the junction voltage of the laser generated in response to the modulated current through said laser; and means for adjusting the laser bias current in response to said error voltage so that the modulated laser current remains above the threshold level of the laser.
Claim 2
Dependent Claim
75 words
An automatic bias control circuit for an injection laser which laser current is modulated in response to a modulating signal comprising: means for deriving an error voltage directly from changes in the junction voltage of the laser generated in response to the modulated current through said laser; and means for adjusting the laser bias current in response to said error voltage so that the modulated laser current remains above the threshold level of the laser.
Claim 3
Dependent Claim
39 words
An automatic bias control circuit in accordance with claim 1 wherein said means for deriving an error voltage includes means for electrically eliminating from the voltage across the laser the voltage drop across the internal resistance of the laser.
Claim 4
Dependent Claim
48 words
An automatic bias control circuit in accordance with claim 1 wherein said means for adjusting the laser bias current includes an envelope detector for determining the maximum amplitude of the error voltage, the laser bias current being adjusted in response to the maximum amplitude of the error voltage.
Claim 5
Dependent Claim
64 words
An automatic bias control circuit in accordance with claim 3 wherein said means for adjusting the laser bias current further includes a current source responsive to the maximum amplitude of said error voltage for generating a current for biasing said laser, the magnitude of said current for biasing being determined by the magnitude of the modulating signal and the threshold level of the laser.
Claim 6
Dependent Claim
92 words
An automatic bias control circuit for an injection laser which laser current is modulated in response to a modulated signal comprising: means for prebiasing said laser with a prebias current having a magnitude below the laser threshold level; means for deriving an error voltage directly from changes in the junction voltage of the laser generated in response to the modulated current through said laser; and means for adjusting the laser bias current in response to said error voltage so that the modulated laser current remains above the threshold level of the laser.
Claim 7
Dependent Claim
92 words
An automatic bias control circuit for an injection laser which laser current is modulated in response to a modulated signal comprising: means for prebiasing said laser with a prebias current having a magnitude below the laser threshold level; means for deriving an error voltage directly from changes in the junction voltage of the laser generated in response to the modulated current through said laser; and means for adjusting the laser bias current in response to said error voltage so that the modulated laser current remains above the threshold level of the laser.
Claim 8
Dependent Claim
39 words
An automatic bias control circuit in accordance with claim 5 wherein said means for deriving an error voltage includes means for electrically eliminating from the voltage across the laser the voltage drop across the internal resistance of the laser.
Claim 9
Dependent Claim
48 words
An automatic bias control circuit in accordance with claim 5 wherein said means for adjusting the laser bias current includes an envelope detector for determining the maximum amplitude of the error voltage, the laser bias current being adjusted in response to the maximum amplitude of the error voltage.
Claim 10
Dependent Claim
69 words
An automatic bias control circuit in accordance with claim 7 wherein said means for adjusting the laser bias current further includes a current source responsive to the maximum amplitude of said error voltage for generating a current additional to said prebias current, the magnitude of the additional current generated being determined by the magnitudes of the modulating signal and the prebias current, and the threshold level of the laser.
References Cited (Backward Citations)
US4019048A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-03-27 | 1981-09-26 | 1982-03-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-03-27 | 1985-09-26 | 1986-03-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-03-27 | 1989-09-26 | 1990-03-28 | $7700.00 | Window Closed / Lapsed |