Laser oscillation Wavelength (λ)
The laser wavelength is represented by the symbol λ, with units of nm.
It is determined by the bandgap of the crystal material of the active layer and the resonator length of the chip structure.
Although there are many candidates for the oscillation wavelength within the resonator length, the laser wavelength at which the most gain is obtained around the bandgap will oscillate.
When the junction (active layer) temperature rises, the resonator length increases physically along with the refractive index, so the laser oscillation wavelength will become longer when the case temperature and light output increase.
Oscillation Wavelength (λ): Measurement Method
The light output of the LD is kept constant using the APC driver.
The laser beam is injected into the optical fiber using a focusing lens and the optical fiber input into the optical spectrum analyzer to observe the oscillation spectrum.