Prism-based tunable InGaN/GaN self-injection locked blue laser diode system: study of temperature, injection ratio, and stability

A quasicontinuously wavelength tuned self-injection locked blue laser diode system employing a prism is presented. A rigorous analysis of the injection ratio (IR) in the form of three systems, namely high (HRS, ∼ − 0.7 dB IR), medium (MRS, ∼ − 1.5 dB IR), and low (LRS, ∼ − 3.0 dB IR) reflection systems, showed a direct relationship with the wavelength tunability whereas the usable system power exhibited an inverse correlation. In particular, MRS configuration demonstrated a concurrent optimization of tuning window and system power, thus emerging as a highly attractive candidate for practical realization. Moreover, a comprehensive investigation on two distinct MRS configurations employing different commercially available InGaN/GaN blue lasers, i.e., MRS-1 and MRS-2, displayed a wavelength tunability (system power) of ∼8.2 nm (∼7.6 mW) and ∼6.3 nm (∼11.6 mW), respectively, at a low injection current of 130 mA. In addition, both MRS configurations maintained high-performance characteristic with corresponding average optical linewidths of ∼80 and ∼58 pm and a side-mode-suppression-ratio of ≥12 dB. Lastly, a thorough stability analysis of HRS and MRS configurations, which are more prone to system instabilities due to elevated IRs, is performed at critical operation conditions of a high injection current of ≥260 mA and a temperature of 40°C, showing an extended stable performance of over 120 min, thus further substantiating the promising features of the prism-based systems for practical applications.