A III-V-on-Si ultra-dense comb laser

Area of Science:

• Photonics and Optical Engineering
• Semiconductor Lasers
• Spectroscopy

Background:

• Optical frequency combs are crucial for high-resolution, near-real-time spectroscopy.
• Current comb generators often rely on bulky, expensive femtosecond lasers.
• Integrated semiconductor lasers face limitations in comb spacing and line count.

Purpose of the Study:

• To demonstrate a compact, low-cost III-V-on-Si comb laser for dense frequency comb generation.
• To overcome limitations of existing integrated semiconductor mode-locked lasers.
• To enable advanced spectroscopy applications through improved frequency comb technology.

Main Methods:

• Integration of a III-V gain material with passive silicon waveguides.
• Design of a long laser cavity enabling passive mode-locking.
• Frequency stabilization of the resulting comb laser.

Main Results:

• Demonstration of a III-V-on-Si comb laser operating at a 1 GHz repetition rate.
• Generation of a dense optical comb with over 1400 equally spaced lines over a 12-nm spectrum.
• Achieved stable mode-locking with sub-kHz radio frequency linewidth and <400 kHz longitudinal mode linewidth.

Conclusions:

• The developed III-V-on-Si comb laser offers a compact and cost-effective solution for dense optical frequency combs.
• This technology significantly enhances the potential for high-resolution and real-time spectroscopy.
• The integrated dense comb lasers pave the way for broader adoption in scientific and industrial applications.