Detuning dependence in current-light-output characteristics of GaN-based DFB laser diodes

We have developed GaN-based laterally coupled distributed-feedback laser diodes (LC DFB-LDs). We focused on the detuning between the DFB-oscillation wavelength and the gain-peak wavelength and systematically investigated the differences in the temperature dependence of the current-light-output ( I -L ) characteristics. As the detuning increased, the rate of temperature change in the threshold current decreased. Furthermore, the I -L characteristics of the DFB-LD with a detuning of +5.3 nm were nearly overlapped within the measured temperature range. Interestingly, the estimated characteristic temperature was negative (−499.4 K). The temperature coefficient of the gain-peak-wavelength shift increased linearly as the detuning increased. On the other hand, the temperature coefficient of the DFB-oscillation-wavelength shift showed a very small dependence on detuning and was 17 pm K −1 . These results provide useful insights for designing light sources with very small temperature dependence or light sources that exhibit the best performance at specific temperatures.