2019/03/31 by Amrit Pal Singh, Stefan Ast, S. Ast +5 · 7 citations
Engineering · Physics and Astronomy · #Advanced Fiber Laser Technologies #Coherent states #Continuous wave #Direct-conversion receiver #Homodyne detection #Laser #Metrology #Modulation (music) #Optics #Phase modulation #Phase noise #Photonic and Optical Devices #Photorefractive and Nonlinear Optics #Physics #Quantum #Quantum entanglement #Quantum noise #Sideband #Spontaneous parametric down-conversion #Squeezed coherent state #Wavelength #quant-ph
paper · pdf · open access · doi:10.1364/oe.27.022408
published in Optics Express 27(16), 22408 (Optica Publishing Group)
arxiv created 2019/05/11 · openalex publication_date 2019/07/23 · arxiv updated 2019/09/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Continuous-wave (cw) squeezed states of light have applications in sensing, metrology and secure communication. In recent decades their efficient generation has been based on parametric down-conversion, which requires pumping by externally generated pump light of twice the optical frequency. Currently, there is immense effort in miniaturizing squeezed-light sources for chip-integration. Designs that require just a single input wavelength are favored since they offer an easier realization. Here we report the first observation of cw squeezed states generated by self-phase modulation caused by subsequent up and down conversions. The wavelengths of input light and of balanced homodyne detection are identical, and 1550 nm in our case. At sideband frequencies around 1.075 GHz, a nonclassical noise reduction of (2.4 ± 0.1) dB is observed. The setup uses a second-order nonlinear crystal, but no externally generated light of twice the frequency. Our experiment is not miniaturized, but might open a route towards simplified chip-integrated realizations.