Passively mode-locked III-V/silicon laser with continuous-wave optical injection.

Area of Science:

• Photonics and Semiconductor Devices
• Integrated Optics
• Telecommunications Technology

Background:

• Quantum well lasers are crucial for telecommunications.
• Silicon photonics offers advantages for integration and cost.
• L-band (1565-1625 nm) operation is vital for dense wavelength-division multiplexing (DWDM).

Purpose of the Study:

• To demonstrate electrically pumped, mode-locked quantum well lasers on silicon.
• To achieve L-band emission with high repetition frequency and output power.
• To improve laser pulse train noise properties using optical injection-locking.

Main Methods:

• Die-to-wafer bonding of III-V quantum wells onto silicon substrates.
• Fabrication of two-section, mode-locked laser structures.
• Application of an optical injection-locking scheme with a continuous-wave (CW) master laser.

Main Results:

• Achieved L-band emission at 30 GHz repetition frequency with >30 dB signal-to-noise ratio.
• Demonstrated 1 mW average output power per facet.
• Reduced radio-frequency (RF) linewidth from 7.6 MHz to 150 kHz via injection locking.
• Decreased pulse-to-pulse jitter to 29.7 fs/cycle and integrated RMS jitter to 1.0 ps.

Conclusions:

• Electrically pumped III-V/Si mode-locked lasers are viable for L-band applications.
• Optical injection-locking effectively suppresses noise and timing jitter in these lasers.
• The improved performance makes these lasers suitable for photonic analog-to-digital converters and clock recovery.