Laser driver circuit with dynamic bias
US4796266A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 21, 1987 |
| Grant date | Jan 3, 1989 |
| Priority date | — |
| Expiry date | Dec 21, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/06835
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The laser driver circuit of the invention stabilizes the low operating output power level of a laser (301) modulated by a digital input signal, at a fixed preset value L.sub.o, by automatically adjusting the bias current, I.sub.b, supplied to the laser to compensate for variations in the laser threshold due to temperature changes and aging. The circuit includes a fast photodetector (401) which is responsive to the modulated light output of the laser. The photodetector output is combined (306, 308) with a data sensitive reference signal (i.sub.r) and a preset level setting input signal (i.sub.o) which is equal to .eta. times the desired low operating output power level L.sub.o, where .eta. is the coupling coefficient of the photodetector. Reference signal i.sub.r varies in accordance with the input data between a zero value when the input is ZERO and a value equal to what is estimated to be the photodetector output due to the data modulation when the input is ONE. The combination of the photodetector output, the data sensitive reference signal i.sub.r, and the level setting input signal i.sub.o, is a difference signal proportional by a factor of .eta. to the difference between the d…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.