Demonstration of a violet-distributed feedback laser with fairly small temperature dependence in current-light characteristics 

Toshihiko Fukamachi¹, Junichi Nishinaka¹, Koichi Naniwae¹, Shuichi Usuda¹, Haruki Fukai¹, Akihiko Sugitani¹, Masahiro Uemukai², Tomoyuki Tanikawa², and Ryuji Katayama²
 

¹Ushio Inc., Japan
²Osaka univ., Japan

Due to the global COVID-19 pandemic from 2020 to 2023, UVC light sources (200–230 nm) that are harmless to the human body have attracted attention. We developed a laterally coupled InGaN DFB-LD emitting around 410 nm with the aim of generating UVC light via second harmonic generation (SHG). The active layer of the fabricated DFB-LD consists of InGaN double quantum wells (DQW), and a regular 3rd-order diffraction grating was employed for the DFB structure. We evaluated the device characteristics by varying the detuning ΔG, defined as the difference between the DFB mode oscillation wavelength λ_DFB and the peak wavelength λ_G of the emission spectrum (ΔG = λ_DFB(25℃) − λ_G(25℃)). As a result, around ΔG = +5 nm, the current–light characteristics overlapped over the temperature range from 25℃ to 80℃. The characteristic temperature at this point was 2550 K, which is 10 to 20 times larger than values previously reported for FP-LDs and similar devices. Furthermore, this result indicates that the device is promising for applications requiring light sources with low temperature dependence of output power without precise temperature control.