Influence of Losses on the Laser Voltage Drop of the Active Section

Abstract

We present a model of a tunable distributed Bragg reflector (DBR) laser describing the effect of cavity losses on the gain voltage. Theoretical and experimental results are in good agreement. Measurements show the gain voltage trace for Bragg grating and phase section tuning. The model is also valid for lasers with optical feedback from an external reflection.

Wavelength Locking and Determination in Tunable Lasers by Gain Voltage Measurement

“…Based on the length of the feedback section and the emitted wavelength, the back reflected beam interferes constructively/destructively according to their phase. This kind of gain/loss can be directly measured by a decrease/increase of the Voltage [9,11]. Hence, a voltage level change indicates either a wavelength change or a change in temperature and with it in the optical length of the feedback section.…”

“…Fig. 6 shows the measured aliasing trace for a Bragg sweep and the corresponding calculated voltage [11]. The oscillation of the voltage is defined by the length difference between the laser cavity Lcav and the feedback cavity Lf.…”

“…However, further investigations [9,10,11] show that the gain voltage can be a wavelength dependent parameter, without any additional equipment but a small reflection outside the laser cavity, which reintroduces parts of the emitted beam back into the laser cavity. This integrated optical feedback makes the gain voltage wavelength dependent and can be used as monitor signal for wavelength locking and wavelength determination.…”