WIDE TEMPERATURE RANGE UNCOOLED TRANSCEVER MODULE FOR UNCONTROLLED ENVIRONMENTS

Abstract

A laser transmitter within an optical transceiver includes a heating element. The heating element is coup led to the laser package and is controlled to allow the laser to be heated to a higher temperature than the ambient temperature when low environmental temperature extremes occur. The transmitter includes a semiconductor laser having an optimal operational temperature range, a laser driver circuit coupled to the laser that provides a modulation current and a bias current to drive the laser, a heating element thermally coupled to the laser and a heating control circuit that monitors the bias current applied to the laser for drops in bias current that are indicative of drops in the surrounding ambient temperature. In response to a drop in bias current, the control circuitry energizes the heating element to provide heat to the laser.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings which illustrate the best mode presently contemplated for carrying out the present invention:

FIG. 1 is an exploded perspective view of coaxial laser and heater element of the present invention;

FIG. 2 is a perspective view of the heater installed adjacent the coaxial laser;

FIG. 3 is a perspective view of the coaxial laser and heater subassembly contained within a pluggable optical transceiver; and

FIG. 4 is a schematic view of the heater driver circuitry of the present invention.

Claims

1. An optical transmitter comprising: a semiconductor laser having an optimal operating temperature range;a heating element thermally coup led to said semiconductor laser;a laser driver circuit configured and arranged to apply a selective bias current to said semiconductor laser to maintain output from said laser at a predetermined constant output level; anda heating control circuit configured and arranged to monitor said bias current applied to said semiconductor laser and energize said heating element in response to a change in said bias current.

2. The optical transmitter of claim 1, wherein said heating element is a flexible resistive heating element.

3. The optical transmitter of claim 1, wherein said semiconductor laser includes an outer housing said heating element being disposed on an outer surface of said outer housing.

4. The optical transmitter of claim 3, wherein said heating element is a flexible resistive heating element that encircles said outer housing,

5. The optical transmitter of claim 1, wherein said laser driver circuit is configured and arranged to monitor output from said semiconductor laser and adjust said bias current to maintain said output at a constant level.

6. The optical transmitter of claim 1, wherein said heating element is a resistive heater, and said heating control circuit is configured and arranged to control a current conducted by said resistive heater responsive to changes in said bias applied to said semiconductor laser.

7. The optical transmitter of claim 1, wherein said semiconductor laser is a distributed feedback semiconductor laser.

8. The optical transmitter of claim 1, further comprising: a housing, said optical transmitter, said heating element, said laser driver and said heating control circuit being received within said housing.

9. A laser transmitter comprising: a housing;a semiconductor laser disposed within said housing, said semiconductor laser having an optimal operating temperature, said semiconductor laser selectively outputting coherent i having a wavelength that changes with decreases in said operating temperature;a driver circuit disposed within said housing said driver circuit being configured and arranged to apply a selective bias current to said semiconductor laser to maintain output from said laser at a predetermined constant level;a heating element thermally coup led to said semiconductor laser; anda heating control circuit, said heating control circuit being configured and arranged to monitor said bias current applied to said semiconductor laser and energize said heating element in response to a drop in said bias current to provide heat to said semiconductor laser, thereby limiting the change in said wavelength output by said semiconductor laser.

10. The laser transmitter of claim 9, wherein said heating element is a flexible resistive heating element.

11. The laser transmitter of claim 9, wherein said semiconductor laser includes an outer housing, said heating element being disposed on an outer surface of said outer housing.

12. The laser transmitter of claim 11, wherein said heating element is a flexible resistive heating element that encircles said outer housing,

13. The laser transmitter of claim 9, wherein said semiconductor laser is a distributed feedback semiconductor laser.