Compact microgear reflector-based laser heterogeneously integrated on a SiN platform.

Area of Science:

• Photonics and Optical Engineering
• Materials Science and Engineering
• Integrated Optics

Background:

• On-chip lasers are crucial for integrated photonic circuits.
• Existing methods for laser integration face challenges in compactness, stability, and fabrication complexity.
• Wavelength-selective elements are key components for laser design and performance.

Purpose of the Study:

• To demonstrate heterogeneously integrated continuous-wave (CW) lasers on a silicon nitride (SiN) platform.
• To utilize a microgear as a wavelength-selective reflector for improved laser performance.
• To enable compact, robust, and frequency-stable on-chip lasers without phase shifters.

Main Methods:

• Heterogeneous integration of laser components onto a SiN platform using micro-transfer printing (µTP).
• Employing a microgear structure as a wavelength-selective reflector within the laser cavity.
• Characterization of laser performance, including output power, linewidth, side-mode suppression ratio (SMSR), and footprint.

Main Results:

• Achieved up to 12.1 mW of on-chip optical output power.
• Demonstrated intrinsic linewidths as narrow as 3.7 kHz, indicating high coherence.
• Lasers operated in single mode with SMSRs exceeding 45 dB.
• Devices exhibit a compact footprint of 4000 × 250 µm².

Conclusions:

• Heterogeneous integration via µTP provides a viable route for fabricating high-performance on-chip lasers.
• The microgear reflector enables compact, stable, and efficient laser operation.
• These integrated lasers show significant potential for applications in coherent communications and LiDAR systems.