On-chip Mach-Zehnder interferometer for 1550 nm laser frequency stabilization

Area of Science:

• Optics and Photonics
• Quantum Physics
• Materials Science

Background:

• Low-noise stable lasers are crucial for advanced scientific applications.
• Semiconductor lasers offer miniaturization potential but often lack intrinsic stability.
• On-chip photonic integrated circuits provide a platform for advanced laser stabilization.

Purpose of the Study:

• To demonstrate the locking of a semiconductor laser to an on-chip silicon nitride Mach-Zehnder interferometer (MZI).
• To utilize Pound-Drever-Hall (PDH) stabilization technology for enhanced laser performance.
• To improve laser frequency noise and stability for metrology, spectroscopy, communication, and quantum physics.

Main Methods:

• Implementing Pound-Drever-Hall (PDH) stabilization technique.
• Locking a semiconductor laser to an on-chip silicon nitride Mach-Zehnder interferometer (MZI).
• Characterizing laser frequency noise and linewidth before and after stabilization.

Main Results:

• Frequency noise suppressed by up to 37 dB.
• Relative frequency stability reached 3 × 10^-10 at 1 ms gate time.
• Laser linewidth narrowed eightfold to 420 kHz at 10 ms integration time.

Conclusions:

• The study successfully demonstrated a method for significantly enhancing semiconductor laser stability using on-chip photonic integration.
• The achieved stability and noise reduction represent an order of magnitude improvement over free-running lasers.
• This technique paves the way for compact, highly stable laser sources for diverse scientific and technological fields.