Green bright squeezed light from a cw periodically poled KTP second harmonic generator

Area of Science:

• Nonlinear optics
• Quantum optics

Background:

• Second harmonic generation (SHG) is a nonlinear optical process.
• Periodically poled crystals like KTP offer advantages for nonlinear frequency conversion.
• Quasi-phase matching (QPM) enables efficient nonlinear interactions.

Purpose of the Study:

• To experimentally demonstrate bright amplitude squeezed light generation.
• To investigate the use of quasi-phase matching (QPM) in a singly resonant SHG.
• To compare the performance of QPM-based SHG with traditional birefringence phase matching.

Main Methods:

• Utilized a singly resonant second harmonic generator (SHG) with a periodically poled potassium titanyl phosphate (KTP) crystal.
• Employed quasi-phase matching (QPM) for efficient nonlinear wave coupling.
• Measured the noise properties of the generated second harmonic field.

Main Results:

• Observed bright amplitude squeezed light.
• Achieved a noise reduction of 13% below the shot noise limit in the second harmonic field.
• Demonstrated that QPM allows access to higher nonlinear tensor elements compared to birefringence phase matching.

Conclusions:

• QPM-based SHG in KTP is an effective method for generating bright amplitude squeezed light.
• The observed noise reduction exceeds that achievable with birefringence phase matching under similar conditions.
• Experimental results show excellent agreement with theoretical predictions.