III-nitride blue microdisk laser diodes are highly desirable in emerging applications, such as augmented reality, virtual reality, and visible light communication. However, the electrically pumped blue microdisk lasers have been lagging for decades owing to weak optical confinement and large internal absorption loss. In this study, the waveguide layers and cladding layers were carefully engineered to enhance the optical confinement and reduce internal absorption loss. Therefore, the first electrically injected blue microdisk laser diodes grown on Si substrates have been successfully fabricated, and exhibited a resistor-capacitance-limited bandwidth of 24.1 GHz, showing highly promising applications in high-speed and large-modulation-bandwidth visible light communication.

GaN-based microdisk laser on Si can be adopted as an efficient on-chip laser source for Si photonics. However, most of the reported microdisk lasers are integrated on Si(111), which is not fully compatible with cost-effective mainstream complementary metal-oxide-semiconductor (CMOS) foundries. In this study, GaN-based microdisk laser monolithically integrated on Si(100) is carefully designed and fabricated thorough wafer bonding and substrate removal. Moreover, it shows 66.5% lower junction temperature due to reduced electric injection power and thermal resistance as compared with the reported conventional GaN-based microdisk lasers grown on Si(111). The result is the roomtemperature continuous-wave current-injected lasing of GaN-based microdisk laser on Si(100), showing a narrow spectral line width of about 0.16 nm and an obvious turning point in the optical output power versus injection current curve.