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US4884278A
Expired / Lapsed
US
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Semiconductor laser modulation control system
Assignee: Fujitsu Ltd
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Filing: 1989-03-06
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Granted: 1989-11-28
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Expires: 2009-03-06
Abstract
Abstract Disclosed is a semiconductor laser modulation control system, and a method thereof. The system includes a drive circuit (1) for supplying a drive current to a semiconductor laser (2) in accordance with an input data, to modulate the input data into an optical signal of the semiconductor laser (2). The optical signal is either at a high intensity state or a low intensity state in accordance with an input data of "1" or "0", in respective time slots of the input data. The system further includes a duty ratio conversion circuit (3) for converting the duty ratio of the input data in such a way that the low intensity state of the optical signal is returned to the high intensity state within each time slot of the input data, whereby the relaxation oscillation is suppressed.
Inventors
- 👤 Hiroshi Nishimoto
- 👤 Takashi Touge
- 👤 Tadashi Okiyama
- 👤 Naoki Kuwata
- 👤 Yasunari Arai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:09
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/062; H01S5/06209; H01S5/06213; H01S5/04; H01S5/042; H01S5/0427
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
138 words
A semiconductor laser modulation control system comprising: a drive circuit (1) for supplying a drive current to a semiconductor laser (2) in accordance with an input data, to modulate said input data into an optical signal of said semiconductor laser (2), said optical signal being at either one of a high intensity state and a low intensity state in accordance with whether said input data is "1" and "0" in respective time slots of said input data; and a duty ratio conversion circuit (3) receiving said input data and having an output connected to an input of said drive circuit (1), for converting the duty ratio of said input data in such a way that said low intensity state of said optical signal is returned to said high intensity state within each time slot of said input data.
Claim 2
Dependent Claim
138 words
A semiconductor laser modulation control system comprising: a drive circuit (1) for supplying a drive current to a semiconductor laser (2) in accordance with an input data, to modulate said input data into an optical signal of said semiconductor laser (2), said optical signal being at either one of a high intensity state and a low intensity state in accordance with whether said input data is "1" and "0" in respective time slots of said input data; and a duty ratio conversion circuit (3) receiving said input data and having an output connected to an input of said drive circuit (1), for converting the duty ratio of said input data in such a way that said low intensity state of said optical signal is returned to said high intensity state within each time slot of said input data.
Claim 3
Dependent Claim
27 words
A semiconductor laser modulation control system as claimed in claim 1, wherein the output signal of said duty ratio converting circuit is a return to one signal.
Claim 4
Dependent Claim
68 words
A semiconductor laser modulation control system as claimed in claim 1, wherein said duty ratio conversion circuit (3) comprises an OR circuit (14) for outputting a logical sum of said input data and a clock signal said clock signal having a high level and a low level in each time slot of said input data, the logical sum being supplied to the input of said drive circuit (1).
Claim 5
Dependent Claim
56 words
A semiconductor laser modulation control system as claimed in claim 1, wherein said drive circuit (1) comprises a field effect transistor having a control electrode connected to the output of said duty ratio conversion circuit, a first electrode connected to said semiconductor laser (2) and a second electrode connected to a power supply (V D ).
Claim 6
Dependent Claim
36 words
A semiconductor laser modulation control system as claimed in claim 4, wherein said semiconductor laser (2) has a cathode connected to said first electrode of said field effect transistor and has an anode connected to ground.
Claim 7
Dependent Claim
27 words
A semiconductor laser modulation control system as claimed in claim 4, wherein a bias current is superposed on the drive current conducted through said field effect transistor.
Claim 8
Independent Claim
117 words
A method for controlling modulation of a semiconductor laser comprising the steps of: (a) supplying a drive current to a semiconductor laser (2) in accordance with an input data, to modulate said input data into an optical signal of said semiconductor laser (2), said optical signal being at either one of a high intensity state and a low intensity state in accordance with whether said input data is "1" or "0" in respective time slots of said input data, and (b) converting a duty ratio of said input data in such a way that said low intensity state of said optical signal is returned to said high intensity state within each time slot of said input data.
Claim 9
Independent Claim
117 words
A method for controlling modulation of a semiconductor laser comprising the steps of: (a) supplying a drive current to a semiconductor laser (2) in accordance with an input data, to modulate said input data into an optical signal of said semiconductor laser (2), said optical signal being at either one of a high intensity state and a low intensity state in accordance with whether said input data is "1" or "0" in respective time slots of said input data, and (b) converting a duty ratio of said input data in such a way that said low intensity state of said optical signal is returned to said high intensity state within each time slot of said input data.
Claim 10
Dependent Claim
24 words
A method for controlling modulation as claimed in claim 7, wherein said converting in step (b) converts the input data into a return-to-one signal.
Claim 11
Dependent Claim
88 words
A semiconductor laser modulation control system for controlling modulation of input data having high and low states, said system comprising: input means for receiving input data having a first duty ratio; and duty ratio converting means for producing an intermediate signal having high and low levels by converting the duty ratio of the input data, the intermediate signal having the high level when corresponding input data is at a high state and has both the high and low levels when the corresponding input data has a low state.
Claim 12
Dependent Claim
88 words
A semiconductor laser modulation control system for controlling modulation of input data having high and low states, said system comprising: input means for receiving input data having a first duty ratio; and duty ratio converting means for producing an intermediate signal having high and low levels by converting the duty ratio of the input data, the intermediate signal having the high level when corresponding input data is at a high state and has both the high and low levels when the corresponding input data has a low state.
Claim 13
Dependent Claim
54 words
A semiconductor laser modulation control system as claimed in claim 9, wherein the intermediate signal has a second duty ratio, and wherein during each occurrence of the low state of the input data the intermediate signal is first at the high level, then at the low level, and finally returns to the high level.
Claim 14
Dependent Claim
75 words
A semiconductor laser modulation control system as claimed in claim 10, wherein said semiconductor laser modulation control system further comprises clock supply means for supplying a clock signal, and wherein said duty ratio converting means comprises an OR circuit for outputting a logical sum of the input data and the clock signal as the intermediate signal, the clock signal having a high level and a low level in each time slot of the input data.
Claim 15
Dependent Claim
57 words
A semiconductor laser modulation control system as claimed in claim 11, further comprising driving means, operatively connected to said duty ratio converting means, for receiving the intermediate signal and supplying a drive current to the semiconductor laser to modulate the input data into an optical signal having high and low intensity states and a third duty ratio.
Claim 16
Dependent Claim
63 words
A semiconductor laser modulation control system as claimed in claim 12, wherein said semiconductor laser modulation control system includes a power supply, and wherein said driving means comprises a field effect transistor having a control electrode connected to the output of said duty ratio converting means, a first electrode connected to the semiconductor laser and a second electrode connected to the power supply.
Claim 17
Dependent Claim
37 words
A semiconductor laser modulation control system as claimed in claim 13, wherein within each time slot the clock signal is first at the high level, then at the low level and finally returns to the high level.
Claim 18
Dependent Claim
33 words
A semiconductor laser modulation control system as claimed in claim 14, wherein the third duty ratio of the optical signal is substantially the same as the second duty ratio of the intermediate signal.
Claim 19
Independent Claim
79 words
A method for controlling modulation using a semiconductor laser, comprising the steps of: (a) receiving input data to be modulated, the input data varying between high and low states, and having a duty ratio therebetween; (b) altering the duty ratio of the input data to obtain both high and low levels when the input data has the low state; and (c) modulating the input data, after said altering of step (b), into an optical signal of the semiconductor laser.
Claim 20
Independent Claim
79 words
A method for controlling modulation using a semiconductor laser, comprising the steps of: (a) receiving input data to be modulated, the input data varying between high and low states, and having a duty ratio therebetween; (b) altering the duty ratio of the input data to obtain both high and low levels when the input data has the low state; and (c) modulating the input data, after said altering of step (b), into an optical signal of the semiconductor laser.
Claim 21
Dependent Claim
42 words
A method for controlling modulation as claimed in claim 16, wherein said altering in step (b) yields a signal having a first high level, then a low level, and finally a second high level where the input data has the low state.
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) | 1992-11-27 | 1993-05-29 | 1993-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-27 | 1997-05-29 | 1997-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-27 | 2001-05-29 | 2001-11-28 | $7700.00 | Window Closed / Lapsed |