US3925735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Modulation apparatus of semiconductor laser device
Assignee: Toshiba Corp
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Filing: 1974-03-26
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Granted: 1975-12-09
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Expires: 1994-03-26
Abstract
Abstract A combination of ''''0'''' and ''''1'''' of a plurality of bits in PCM (pulse code modulation) signal is detected to reduce the PCM pattern effect of laser outputs resulting from the direct current modulation of a semiconductor laser device by PCM current pulses. Compensation pulses are formed when a succeeding bit is ''''1'''' and when at least one preceding bit is ''''0.'''' The compensation current pulse is superposed on the modulation current pulse of the succeeding bit applied to the laser device.
Inventors
- 👤 Takeshi Ozeki
- 👤 Takao Ito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:55
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; H04B10/508; H04B10/516; H04B10/524
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
130 words
AppAratus for modulating a current-modulated semiconductor laser comprising: a laser diode means responsive to a modulation signal current flowing therethrough to emit a laser beam; a source of modulation signal which is pulsed on and off according to an information signal; first circuit means responsive to said modulation signal to produce a compensation pulse when a one-bit modulation pulse arrives after one or more bit time intervals in which there exist no modulation pulses; second circuit means connected to said laser diode means to cause a compensation current pulse to flow through said laser diode in response to said compensation pulse; and third circuit means connected to said laser diode means to cause a modulation signal current to flow through said laser diode means in response to said modulation signal.
Claim 2
Dependent Claim
130 words
AppAratus for modulating a current-modulated semiconductor laser comprising: a laser diode means responsive to a modulation signal current flowing therethrough to emit a laser beam; a source of modulation signal which is pulsed on and off according to an information signal; first circuit means responsive to said modulation signal to produce a compensation pulse when a one-bit modulation pulse arrives after one or more bit time intervals in which there exist no modulation pulses; second circuit means connected to said laser diode means to cause a compensation current pulse to flow through said laser diode in response to said compensation pulse; and third circuit means connected to said laser diode means to cause a modulation signal current to flow through said laser diode means in response to said modulation signal.
Claim 3
Dependent Claim
54 words
Apparatus according to claim 1 wherein said first circuit means comprises a delay circuit means coupled to said modulation signal source, a delay flip-flop circuit means coupled to said delay circuit means, and a logic circuit means coupled to said modulation signal source and said delay flip-flop circuit means to produce said compensation pulse.
Claim 4
Dependent Claim
15 words
Apparatus according to claim 1 wherein said third circuit means comprises a delay circuit means.
Claim 5
Dependent Claim
45 words
Apparatus according to claim 1 wherein said first means comprises a shift register means having a plurality of stages connected in cascade for storing said modulation signal, and a logic circuit means responsive to outputs of said shift register means to produce said compensation pulse.
Claim 6
Dependent Claim
19 words
Apparatus according to claim 4 wherein each stage of said shift register means consists of a delay flip-flop circuit.
Claim 7
Dependent Claim
88 words
Apparatus according to claim 1 wherein said first circuit means comprises a shift register means having at least three stages connected in cascade for storing said modulation signal, a logic circuit means responsive to outputs of said shift register means to produce said compensation pulse, and means for selectively causing said logic circuit means to produce said compensation pulse in response to outputs of at least two preceding stages of said shift register means irrespective of output of at least one succeeding stage of said shift register means.
Claim 8
Dependent Claim
37 words
Apparatus according to claim 1 wherein said second means comprises a transistor having a collector-emitter path coupled in series with said laser diode means across a power source, and a base coupled to said first circuit means.
Claim 9
Dependent Claim
39 words
Apparatus according to claim 1 wherein said third circuit means comprises a transistor having a collector emitter path coupled in series with said laser diode means across a power source, and a base coupled to said modulation signal source.
Claim 10
Independent Claim
82 words
A method of modulating a current-modulated semiconductor laser comprising the steps of: supplying a modulation signal current which is pulsed on and off according to an information signal to a laser diode; producing a compensation pulse when a one-bit modulation pulse arrives after one or more bit time intervals in which there exist no modulation pulses; and supplying a compensation current pulse to said laser diode substantially at the same time when said one-bit modulation pulse is applied to said laser diode.
Claim 11
Independent Claim
82 words
A method of modulating a current-modulated semiconductor laser comprising the steps of: supplying a modulation signal current which is pulsed on and off according to an information signal to a laser diode; producing a compensation pulse when a one-bit modulation pulse arrives after one or more bit time intervals in which there exist no modulation pulses; and supplying a compensation current pulse to said laser diode substantially at the same time when said one-bit modulation pulse is applied to said laser diode.
Claim 12
Dependent Claim
22 words
A method according to claim 9 further comprising the step of delaying the modulation signal current relative to the compensation pulse current.
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) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |