Lateral power-monitoring photodiode monolithically integrated into 1.3 μm GaInAsP laser

This study describes a method to produce a novel Lateral-side Power-Monitoring Photodiode (Lateral PMD) and a ridge stripe waveguide Laser Diode (LD) integrated into a monolithic structure using conventional laser process technology. Compared with the LDs of traditional monolithically integrated Rear-side Power-Monitoring Photodiodes (Rear PMDs), the cleaved facets in the new structural LDs remain undamaged, and therefore have a lower threshold current (28 mA) and red-shift rate (0.31 nm/°C) and higher slope efficiency (11.93%). In addition, the characteristics are close to those of a conventional LD. Furthermore, under −0.2 V, the Lateral PMD still provides high linear monitoring capabilities for an LD with a light output power of 8.33 mW. Even after long periods of operation, the variations in LD output power and Lateral PMD photocurrent both fall within a range of 1%. This indicates that a monolithically integrated Lateral PMD is extremely reliable.

► A novel Lateral PMD is monolithically integrated into a ridge laser.
► The LD with Lateral PMD provides greater LD quality than that of the Rear PMD.
► The Lateral PMD provides superior linear monitoring ability and power consumption.
► The LD and Lateral PMD maintain similar variations for long periods.
► The low cost approach and reliability release the barrier for future mass production.