Silicon photonics hybrid wavelength tunable laser diode using curved directional couplers with 145 nm tunable range

The expansion of the wavelength tunable range of wavelength tunable laser diodes is required in optical communication and sensing. Curved directional couplers (DCs) exhibit smaller power coupling efficiency fluctuations than conventional straight DCs, which reduces the wavelength sensitivity of double-ring wavelength filters. In this study, we fabricated a hybrid wavelength tunable laser diode comprising curved DCs with an improved design. This laser diode had a wavelength tunable range of 145.2 nm, which is the broadest tunable range as an external-cavity laser diode with silicon waveguides.