Advantages of TEC Stabilized Lasers
Peltier coolers, also referred to as thermo-electric cooler (TEC), is an electronics device composed of two ceramic substrates (hot side and cold side) and multiple thermo-electric crystals in between.
The function of a Peltier cooler is to create a temperature difference between those two ceramic plates though provision of electric current.
Advantages of TEC stabilized lasers
Peltier coolers provide many benefits for lasers. Main advantages include central wavelength control, increased power amplitude stability and decreased RIN noise.
In the most simple case of a CW direct diode laser, Peltier is used to stabilize or sometimes tune the central wavelength of the laser. This is particularly important in spectroscopic applications or systems having steep-edge optical bandpass filters. There are several effect, how change of laser central wavelength might result in worse power amplitude stability.
The most obvious one is in a system with optical bandpass filters. Whether some optical components (e.g. filter) have a spectral transmission/reflection slope, change of central wavelength will result in different percentage of light being transmitted/reflected.
Another source for instabilities is non-flat response of photodiodes, which are generally used to stabilize output power of a laser. Each photodiode has its own spectral sensitivity peaks. Whether the change of laser central wavelength appears in the range where a photodiode has significant sensitivity slope, the output power will change along with the central wavelength.