Quantum-noise measurements in high efficiency single-pass sum-frequency generation with femtosecond pulses

Summary form only given. Reports quantum noise measurements in a high-efficiency single-pass sum-frequency generation (SFG) system with a mode-locked femtosecond pulse laser in a noncritical type-I phase-matched KNbO/sub 3/ crystal. The conversion efficiency from fundamental pulses (with a center wavelength at 857.7 nm and a broad spectral linewidth >12 nm) to blue light pulses (with a wavelength at 428.8 nm and a narrow spectral linewidth <9.5 nm) can be greater than 60%. Since the phase-matching width of the KNbO/sub 3/ crystal is only about 0.7 nm, the main mechanism for the blue light generation is the SFG from the pairs of frequency components of the fundamental pulses. The quantum noise on the blue light was observed to be 1.0 dB (1.4 dB inferred) below the shot-noise limit in certain condition. To our knowledge, this is the first quantum noise measurement done in strong pump-depletion region.