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Journal of the Optical Society of America B

Quantum correlation between fundamental and second-harmonic fields via second-harmonic generation

Yongmin Li, Sujing Zhang, Jianli Liu, Kuanshou Zhang

Published Feb 15, 2007• 10 citations
Publisher

Abstract

We experimentally demonstrated the quantum anticorrelation between fundamental (1064 nm) and second-harmonic (532 nm) fields in an external cavity-enhanced singly resonant periodically poled KTP (PPKTP) frequency doubler. Fundamental amplitude squeezing of 0.5 dB and second-harmonic amplitude squeezing of 0.3 dB were generated simultaneously at a pump power of 6.1 mW. Meanwhile, quantum anticorrelation of 0.64 dB between the squeezed fundamental and the second-harmonic fields was observed.

DOI
10.1364/josab.24.000660

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We experimentally demonstrated the quantum anticorrelation between fundamental (1064 nm) and second-harmonic (532 nm) fields in an external cavity-enhanced singly resonant periodically poled KTP (PPKTP) frequency doubler. Fundamental amplitude squeezing of 0.5 dB and second-harmonic amplitude squeezing of 0.3 dB were generated simultaneously at a pump power of 6.1 mW. Meanwhile, quantum anticorrelation of 0.64 dB between the squeezed fundamental and the second-harmonic fields was observed.
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We demonstrate a high-efficiency green light conversion from an external cavity second harmonic generation with a MgO-doped periodically poled LiNbO 3 crystal. The frequency doubler can reach a conversion efficiency of 64% with a fundamental power of 26 mW. Meanwhile, the generated green light is quadrature-amplitude squeezed and 1.2 dB green light squeezing is experimentally measured. The squeezing at different pump levels is also investigated and is in good agreement with the theoretical prediction.
We demonstrate production of short wavelength beams with nonclassical intensity correlations and quadrature entanglement using second harmonic generation in a nonlinear resonator with two output ports. The two output beams at the harmonic frequency have no direct interaction but are both nonlinearly coupled to a common pump beam. The nonlinear coupling produces amplitude and phase correlations between the beams which results in quadrature entanglement. The output beams at λ = 428.5 nm are shown to exhibit 0.6 dB of amplitude quadrature squeezing, 0.9 dB of nonclassical intensity correlations, and 0.3 dB of entanglement using about 30 mW of pump power.