Yes, both optical output power and spectral properties depend on the SLED chip temperature. All standard EXALOS products packaged in a DIL or a Butterfly package contain a Thermo Electric Cooler (TEC) inside the package to thermally stabilize the SLED. Standard low-cost EXALOS SLEDs packaged in a TO-CAN or TOSA devices do not have a TEC included. As a rough guide, the center wavelength changes with temperature at a rate of approximately 0.3nm/°C (0.7nm/°C) for short (long) wavelength devices.