Reduction of relative intensity noise in a diamond Raman laser

Area of Science:

• Laser Physics
• Nonlinear Optics
• Materials Science

Background:

• Continuous-wave diamond Raman lasers are crucial for various applications.
• Relative intensity noise (RIN) is a key parameter affecting laser performance.
• Parasitic stimulated Brillouin scattering (SBS) is known to degrade laser properties.

Purpose of the Study:

• To investigate the relative intensity noise (RIN) characteristics of a continuous-wave diamond Raman laser for the first time.
• To identify the impact of parasitic stimulated Brillouin scattering (SBS) on RIN.
• To explore methods for RIN reduction in diamond Raman lasers.

Main Methods:

• Experimental investigation of RIN in a diamond Raman resonator.
• Suppression of parasitic SBS using a spatial aperture.
• Suppression of parasitic SBS using a χ(2) nonlinear crystal.
• Analysis of Raman longitudinal modes and RIN levels.

Main Results:

• Parasitic SBS significantly impacts Raman longitudinal modes and deteriorates RIN.
• Effective suppression of SBS leads to single-longitudinal-mode operation and reduced RIN (200 Hz to 1 MHz).
• A χ(2) nonlinear crystal offers superior RIN reduction compared to a spatial aperture due to additional nonlinear loss.

Conclusions:

• Parasitic SBS is a critical factor limiting RIN performance in diamond Raman lasers.
• Both spatial apertures and χ(2) nonlinear crystals can effectively suppress SBS and reduce RIN.
• The χ(2) nonlinear crystal method provides enhanced RIN reduction, paving the way for high-power, low-noise lasers across various wavelengths and crystalline media.