Home > FAQs > Light Emitting Diodes (SLED)- Monitor Photo Diodes (MPD)
Operating SLEDS
OPERATING EXALOS SLEDs AND CONTROLLERS
What is the operating temperature range?
Are EXALOS products thermally stablized?
How should I control the superluminescent light emitting diodes' (SLEDs') temperature?
Where is the TEC located and how is the heat dissipated?
Why is the Butterfly package better for high power devices than DIL?
What is the maximum forward current?
Does EXALOS provide a laser diode controller or a TEC driver?
How can I use the Monitor Photo Diode (MPD)?
OPERATING EXALOS SLEDs AND CONTROLLERS
What is the operating temperature range?The operating temperature range over which superluminescent light emitting diodes (SLEDs) modules can be operated is given in the specification for that SLED. It is typically between -20°C and 65°C.
The chip temperature should be set to 25°C for the short-wavelength SLEDs (730 to 900nm) and to 20°C for the long-wavelength SLEDs (1250 to 1700nm). The SLEDs can be operated at slightly modified temperatures, but care should be taken not to exceed the maximum current ratings given in the specification. This is especially true when operating the devices at lower temperatures, where higher power levels can be achieved.
Are EXALOS products thermally stablized?
All standard EXALOS products packaged in DIL or Butterfly package contain a Thermo Electric Cooler (TEC) inside the package to thermally stabilize superluminescent light emitting diodes (SLEDs). SLEDs packaged as TOSAs (pigtailed) or in a TO-can are low cost devices and are not thermally stabilized as standard.
How should I control the superluminescent light emitting diodes' (SLEDs') temperature?
All standard EXALOS products packaged in DIL or Butterfly package contain a Thermo Electric Cooler (TEC) inside the package and a negative temperature coefficient (NTC) thermistor is placed in close proximity to the SLED chip. Employing a suitable external heat sink and control electronics allows for the stabilization of the chip temperature against environmental variations.
As standard, the chip temperature should be set to 25°C for the short-wavelength SLEDS (730 to 900nm) and to 20°C for the long-wavelength SLEDs (1250 to 1700nm). Please ask for our Application Notes for more details.
Where is the TEC located and how is the heat dissipated?
The superluminescent light emitting diodes (SLEDs) chip is mounted on a submount that is fixed on top of the TEC. Depending on the type of package, the generated heat is transferred either directly to the bottom of the package (Butterfly) or to the back face of the package (DIL).
Why is the Butterfly package better for high power devices than DIL?
High power devices are generally operated at higher drive currents and therefore, generate more heat. In a Butterfly package the generated heat is transferred directly to the bottom of the package where it can be dissipated efficiently. In contrast, in a DIL package the heat path is less efficient as the heat is transferred to the back face.
What is the maximum forward current?
The maximum forward current depends on the exact type of superluminescent light emitting diodes (SLEDs) and can be on the product overview. Any values in excess of the stated maximum ratings should be avoided.
Does EXALOS provide a laser diode controller or a TEC driver?
EXALOS provides a low-cost driver unit that allows easy use of superluminescent light emitting diodes (SLEDs). The driver controls both the SLED current and the TEC inside the SLED package. The driver board specification can be found on product overview page.
How can I use the Monitor Photo Diode (MPD)?
The monitor photo diode (MPD) can be used to monitor and control the output power and guarantee performance over various operating conditions and over time. The generated photocurrents are in the mA range, eliminating the need for further amplification such as a transimpedance amplifier.
