A micrometre-scale Raman silicon laser with a microwatt threshold

Area of Science:

• Photonics and Materials Science
• Integrated Optics
• Semiconductor Lasers

Background:

• Moore's Law limitations drive research into novel silicon electronics.
• Silicon photonics aims for integrated circuits compatible with complementary metal-oxide-semiconductor technology.
• Exploiting the Raman effect in silicon has enabled active optical functionality, including all-silicon lasers.

Purpose of the Study:

• To overcome limitations of existing silicon Raman lasers, specifically size and high lasing thresholds.
• To demonstrate a miniaturized, low-power continuous-wave all-silicon Raman laser.
• To enable practical silicon lasers for large-scale photonic integration.

Main Methods:

• Utilized a photonic-crystal, high-quality-factor nanocavity.
• Designed the nanocavity to enhance light-matter interactions by maximizing the quality factor to volume ratio.
• Operated the laser without reverse-biased p-i-n diodes.

Main Results:

• Achieved a continuous-wave Raman silicon laser with a cavity size under 10 micrometres.
• Demonstrated an unprecedentedly low lasing threshold of 1 microwatt.
• Significantly enhanced Raman gain beyond theoretical predictions.

Conclusions:

• The developed nanocavity design drastically enhances Raman gain in silicon.
• This breakthrough paves the way for practical, miniaturized silicon lasers.
• The technology is suitable for large-scale integration into photonic circuits.