Temperature-insensitive frequency conversion by phase mismatch self-compensation in the same type of crystals

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• High-power laser systems require efficient frequency conversion.
• Thermally induced phase mismatch is a major limitation in laser frequency conversion.
• Existing methods for thermal compensation are often complex or limited in applicability.

Purpose of the Study:

• To present a new scheme for self-compensating thermally induced phase mismatch in laser frequency conversion.
• To experimentally demonstrate the effectiveness of the proposed scheme for temperature-insensitive harmonic generation.
• To highlight the universal applicability of the scheme for various laser frequency conversion processes.

Main Methods:

• Cascading three identical crystals for frequency conversion and phase mismatch compensation.
• Configuring polarization states in the middle crystal to achieve opposite temperature derivatives of phase mismatch.
• Experimental demonstration using potassium dihydrogen phosphate (KH2PO4) crystals for second and third harmonic generation.

Main Results:

• Successful demonstration of temperature-insensitive second and third harmonic generation.
• Achieved a temperature acceptance bandwidth approximately two times larger than single-crystal configurations.
• Validated the scheme's broad applicability across different laser wavelengths, crystal types, and phase-matching types.

Conclusions:

• The proposed three-crystal scheme effectively self-compensates for thermally induced phase mismatch.
• The method significantly enhances temperature insensitivity and broadens the operational bandwidth for laser frequency conversion.
• This universally applicable scheme offers a robust solution for high-power laser frequency conversion with minimal limitations.