Wide temperature range vertical cavity surface emitting laser
View Patent ↗A vertical cavity surface emitting laser (VCSEL) module that is configured to operate in a wide temperature range without severely minimizing its lifetime or requiring excessive drive current. The VCSEL portion of the VCSEL module is tuned to operate efficiently at a higher than normal temperature. In addition to the VCSEL, the VCSEL module includes a heater and a temperature sensor that are used to maintain a particular minimum temperature that is within the efficient operation range of the VCSEL. By maintaining a temperature that is within the efficient operation range, the VCSEL module reduces the current required to operate the VCSEL and extends the overall lifetime of the VCSEL. The additional components of the VCSEL module do not interfere in any way with the signal quality produced by the VCSEL.
1. A vertical cavity surface emitting laser (VCSEL) module, comprising:
a VCSEL;
a temperature sensor configured to sense an operating temperature of the VCSEL;
a heating element in thermal communication with the VCSEL; and
a control module in communication with the temperature sensor and operably connected with the heating element and with the VCSEL, and the control module configured to operate in:
a first operational mode where a change in operating temperature of the VCSEL is associated with a VCSEL operating current output of the control module; and
a second operational mode where a change in operating temperature of the VCSEL is associated with a heating element control output of the control module, the heating element control output corresponding with a thermal output of the heating element;
wherein a drop in VCSEL operating temperature below an activation temperature is associated with either:
a corresponding relative increase in the VCSEL operating current output of the control module; or
a corresponding change in a heating element control output of the control module; and
wherein the control module is configured to operate in whichever operational mode requires the least amount of energy, relative to the other operational mode.
2. A module as defined in claim 1 , wherein at the predetermined operating temperature, a cavity resonance point of the vertical cavity surface emitting laser is substantially aligned with a gain bandwidth peak of the vertical cavity surface emitting laser.
3. A module as defined in claim 1 , wherein the temperature sensor comprises a thermistor.
4. A module as defined in claim 1 , wherein the heating element comprises a resistor.
5. A module as defined in claim 1 , wherein the predetermined operating temperature is greater than 30 degrees Celsius.
6. A module as defined in claim 1 , wherein the predetermined operating temperature is greater than about 50 degrees Celsius.
7. A module as defined in claim 1 , wherein the predetermined operating temperature is about 70 degrees Celsius.
8. A module as defined in claim 1 , wherein the control module turns the heating element off when the operating temperature exceeds the predetermined operating temperature.