On-chip light detection using integrated microdisk laser and photodetector bonded onto Si board
Characteristics of a compact III–V optocoupler heterogeneously integrated on a silicon substrate
and formed by a 31 μm in diameter microdisk (MD) laser with a closely-spaced
50 μm × 200 μm waveguide photodetector are presented. Both optoelectronic devices were
fabricated from the epitaxial heterostroctructures with InGaAs/GaAs quantum well-dot layers.
The measured dark current density of the photodetector was as low as 2.1 μA cm−2. The
maximum link efficiency determined as the ratio of the photodiode photocurrent increment to
the increment of the microlaser bias current was 1%–1.4%. The developed heterogeneous
integration of III–V devices to silicon boards by Au-Au thermocompression bonding is useful
for avoiding the difficulties associated with III–V epitaxial growth on Si and facilitates
integration of several devices with different active layers and waveguides. The application of
MD lasers with their lateral light output is promising for simplifying requirements for optical
loss at III–V/Si interface.