It is well known that varying the temperature of a laser diode (which is a type of laser emitter) may affect the wavelength (λ) of the emitted optical signal. For some applications, the wavelength of the optical signal is not critical, and a heat sink is generally sufficient for cooling a laser diode for these applications. Optical signals with precise wavelengths are required for some applications such as Dense Wavelength Division Multiplexing (DWDM), however. For those applications, a laser diode must be maintained at a precise temperature, and a heat sink alone is not sufficient.
Some conventional laser diode packages contain a large built-in temperature controller to control the temperature of the laser diode. Some laser packages even contain an elaborate built-in coolant-circulation system for cooling the laser diode. Because of their large size, such conventional laser diode packages cannot be easily incorporated into pluggable fiber optic transceiver or transmitter modules, which typically have strict form factor requirements.
In addition, conventional laser diode packages containing large built-in temperature controllers consume a significant amount of power. Many industry standards for pluggable transceiver or transmitter module have strict limitations on power consumption. These limitations make it even more difficult to incorporate conventional laser packages with large temperature controllers into pluggable transceiver or transmitter modules.
Accordingly, there exists a need for an apparatus for precisely controlling the temperature of a laser diode without using a laser diode package that contains a large built-in temperature controller such that temperature control functionality can be implemented in an optoelectronic transceiver or transmitter modules.