A 10-kHz intrinsic linewidth coupled extended-cavity DBR laser monolithically integrated on an InP platform.

Area of Science:

• Photonics and Semiconductor Lasers
• Integrated Optics
• Quantum Technologies

Background:

• Narrow linewidth lasers are crucial for high-resolution spectroscopy and quantum communications.
• Achieving ultra-low linewidths in monolithic integrated lasers remains a significant challenge.
• Existing integrated laser technologies often struggle to meet the stringent linewidth requirements for advanced applications.

Purpose of the Study:

• To demonstrate a monolithically integrated coupled extended-cavity distributed Bragg reflector laser.
• To achieve the lowest reported intrinsic linewidth for such a device.
• To explore the potential for integration with other photonic components.

Main Methods:

• Fabrication of a coupled extended-cavity distributed Bragg reflector laser on an Indium Phosphide (InP) foundry platform.
• Characterization of laser performance, including optical output power, side-mode suppression ratio, and frequency noise.
• Measurement of the intrinsic linewidth using the delayed self-heterodyne method.

Main Results:

• Achieved an intrinsic linewidth of approximately 10 kHz, corresponding to a frequency noise level of ~3200 Hz²/Hz.
• Experimentally measured linewidth of 45 kHz.
• Obtained an on-chip optical output power of 18 mW at 1550 nm with a 95 mA injection current.
• Demonstrated single-mode operation with a side-mode suppression ratio of 54 dB.

Conclusions:

• The developed monolithic integrated laser exhibits the lowest reported intrinsic linewidth, demonstrating significant progress in integrated photonics.
• The device's performance highlights the potential of the InP platform for high-performance photonic integrated circuits.
• This monolithic approach facilitates further integration, enabling applications such as integrated quantum key distribution transceivers.