Research Of Quantum Sources Based On Silicon Waveguides

Since the silicon waveguide has a high third-order optical nonlinear coefficient and strong light-limiting ability,its optical nonlinear effect has been widely studied.Combined the advantages of excellent optical nonlinearity and mature silicon waveguide fabrication processes and high integration,silicon waveguides have been used for new types of quantum sources,which has excellent application prospects in fields such as quantum communication and quantum simulation.In this paper,the mechanism,scheme,and testing of the correlated photon pairs generated by silicon waveguides are studied systematically.The photon pair generation rate of 200 KHz and the quantum interference of 73.4% visibility were realized,and the correlated photon pairs are used to achieve the measurement of fiber dispersion.Firstly,we analyze the basic principle of four-wave mixing and phase matching conditions.The relationship between dispersion curves and structural parameters of silicon waveguides was obtained by numerical simulation.It's found that silicon waveguide shows slight anomalous dispersion and is in a single-mode state with a width of 500 nm and a height of 220 nm,which is very suitable for realizing the good phase matching.According to above parameter,the 6 mm silicon waveguide was fabricated with a transmission loss of 5 dB/cm.Then four-wave mixing was tested with the conversion efficiency of-22 dB and 3 dB bandwidth of 15 nm.Then,silicon waveguide was pumped by a monochromatic laser to generate nondegenerate time-energy entangled photon pairs under the spontaneous four-wave mixing process,and the relationship between photon pair generation rate and pump power was explored.Secondly,Franson interference is performed on the non-degenerate time-energy photon pairs.Interference fringes with a period of ? and an interference visibility of 49.2 ?2.8% were obtained.The measurement results are in good agreement with the theoretical analysis.In order to improve the visibility of interference,it is proposed to use silicon microrings to filter the generated photon pairs on-chip to obtain narrow linewidth photon pairs.Under this scheme,we prepared a degenerate time-energy entangled photon pair with 3 dB line width of approximately 6.25 G.Interferometric visibility increased to 73.4% ?7% when Franosn interference was performed on the degenerate time-energy entangled photon pairs.Finally,multiple pairs of non-degenerate time-energy entangled photon pairs generated in straight waveguides are introduced into the dispersion fiber.After passing through the same segment of dispersive fiber,a delay will occur between the two photons.By recording the delays of pairs of correlated photon pairs,a dispersion coefficient measurement of a dispersion-compensating fiber with a length of 2 km is achieved.The measurement result is consistent with the results of commercial dispersion measurement equipment,and at the same time,we explain the broadening of the coincidence count spectrum in the dispersion measurement.