Wide temperature range uncooled transceiver module for uncontrolled environments
View Patent ↗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.
1. An optical transmitter comprising:
a semiconductor laser having a package that includes an outer surface and an optimal operating temperature range;
a heating element disposed about said outer surface of 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 level; and
a heating control circuit that monitors said bias current applied to said semiconductor laser and energizes said heating element in response to a drop 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 laser drive circuit monitors output from said semiconductor laser and adjusts said bias current to maintain said output at a constant level.
4. The optical transmitter of claim 1 , wherein said heating element is a resistive heater, and said heating control circuit controls a current conducted by said resistive heater in response to changes in said bias applied to said semiconductor laser.
5. The optical transmitter of claim 1 , wherein said semiconductor laser is a distributed feedback laser.
6. The optical transmitter of claim 1 , further comprising:
a housing, said optical transmitter, said heating element, said laser driver and said heating control circuit a received within said housing.
7. 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 radiation having a wavelength that changes with decreases in said operating temperature;
a driver circuit disposed within said housing, said 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 level;
a heating element thermally coupled to said semiconductor laser; and
a heating control circuit mounted in said housing, said heating control circuit monitoring said bias current applied to said semiconductor laser and energizes said heating element in response to a drop in said bias current to provide heat to said semiconductor laser, thereby limiting the variation in said wavelength output by said semiconductor laser.
8. The laser transmitter of claim 7 , wherein said heating element is a flexible resistive heating element.
9. The laser transmitter of claim 7 , said semiconductor laser having an outer housing, said heating element being installed on an outer surface of said outer housing.
10. The laser transmitter of claim 9 , wherein said heating element is a flexible resistive heating element that is wrapped around said outer housing.
11. The laser transmitter of claim 7 , wherein said semiconductor laser is a distributed feedback laser.