Self-linewidth-narrowing photonic oscillator.

Area of Science:

• Photonics
• Laser Physics
• Optical Engineering

Background:

• Achieving ultra-high spectral purity in lasers is crucial for many scientific and technological applications.
• Traditional methods for laser stabilization often involve complex and bulky electronic servo-locking systems.
• Semiconductor lasers, while versatile, typically suffer from limited spectral purity compared to other laser types.

Purpose of the Study:

• To present a novel self-adaptive photonic oscillator design for achieving exceptional spectral purity.
• To demonstrate single-frequency operation without the need for external electronic stabilization.
• To explore the potential of this principle for various wavelength applications.

Main Methods:

• Utilizing a 100-m-long active optical resonator coupled with a standard semiconductor laser.
• Employing stimulated Brillouin scattering as the coupling mechanism between the laser and resonator.
• Operating the system in a free-running configuration without servo-locking or stabilization electronics.

Main Results:

• The self-adaptive photonic oscillator demonstrated a Lorentzian linewidth of 40 mHz.
• A Flicker noise linewidth of 200 Hz was measured for a 0.01 s integration time.
• Long-term optical frequency drift was observed to be approximately 10 MHz over several hours, without absolute frequency locking.

Conclusions:

• The proposed self-adaptive oscillator principle offers a pathway to ultimate spectral purity in lasers.
• This method simplifies laser stabilization, removing the need for complex electronic systems.
• The principle's applicability across various wavelengths opens significant opportunities for precision spectroscopy and metrology.