Integrated GaInAsP laser diodes with monitoring photodiodes throughsemiconductor/air Bragg reflector (SABAR)

摘要

A 1.3-Μm GaInAsP laser diode (LD) is integrated with anmonitoring photodiode (M-PD) through a semiconductor/air Bragg reflectorn(SABAR). Instead of conventional cleavage, the SABAR can provide notnonly Fabry-Perot resonance with high reflectivity, but also possibilitynof integration of laser with other functional devices. The design,nfabrication, and some characteristics including threshold current,nmonitoring photocurrent, SABAR reflectivity as a function of the numbernof semiconductor/air pairs N are reported. The threshold current ofnridge waveguide laser with SABAR (cavity length L=160 Μm, ridge widthnW=7 Μm, SABAR pairs N=3) is 20 mA. The threshold current is reducednby improving butt-coupled interface between active and passivenwaveguides employed in this laser and is expected 2 mA/Μm. Thenmonitoring photocurrent responds linearly with output power from thenlaser and 0.024 mA at laser output power of 5 mW. From the thresholdncharacteristics, SABAR reflectivity is determined to >80%. Thenincrease of photocurrent can be achieved by optimizing the number ofnSABAR pairs to N=1. We have obtained threshold current of 22 mA in thenfollowed laser structure (L=270 Μm, W=7 Μm, N=1), and detectornphotocurrent of 1.13 mA (@5 mW). The experimental SABAR reflectivity isn~50%, which is estimated by threshold characteristics and efficiency ofnlight output power. The laser has a mode field converter section,nresulting in narrow beam divergence 11° along vertical axis. Thisnintegrated laser is very promising candidate for coming optical modulenin low-power consumption and low-cost access network systems