Characterize and optimize the four-wave mixing in dual-interferometer coupled silicon microrings

By designing and fabricating a series of dual-interferometer coupled silicon microrings, the coupling condition of the pump, signal, and idler beams can be engineered independently and then we carried out both the continuous-wave and pulse pumped four-wave mixing experiments to verify the dependence of conversion efficiency on the coupling conditions of the four interacting beams, respectively. Under the continuous-wave pump, the four-wave mixing efficiency gets maximized when both the pump and signal/idler beams are closely operated at the critical coupling point, while for the pulse pump case, the efficiency can be enhanced greatly when the pump and converted idler beams are all overcoupled. These experiment results agree well with our theoretical calculations. Our design provides a platform for explicitly characterizing the four-wave mixing under different pumping conditions, and offers a method to optimize the four-wave mixing, which will facilitate the development of on-chip all-optical signal processing with a higher efficiency or reduced pump power.

CL-TWE Mach–Zehnder electro-optic modulator based on InP-MQW optical waveguides

In this Letter,we reported the preliminary results of an integrating periodically capacitive-loaded traveling wave electrode(CL-TWE)Mach–Zehnder modulator(MZM)based on InP-based multiple quantum well(MQW)optical waveguides.The device configuration mainly includes an optical Mach–Zehnder interferometer,a direct current electrode,two phase electrodes,and a CL-TWE consisting of a U electrode and an I electrode.The modulator was fabricated on a 3 in.InP epitaxial wafer by standard photolithography,inductively coupled plasma dry etching,wet etching,electroplating,etc.Measurement results show that the MZM exhibits a3 dB electro-optic bandwidth of about 31 GHz,a Vπof 3 V,and an extinction ratio of about 20 dB.

Bright photon-pair source based on a silicon dual-Mach-Zehnder microring

Single photons and photon pairs are typically generated by spontaneous parametric down conversion or quantum dots;however,spontaneous four-wave mixing(SFWM)in silicon microring resonators[1]is also an appealing source of entangled photons,offering a strong cavity-enhanced nonlinear interactions while maintaining features,such as compact,simple to fabricate,and allowing for thermal tuning.However,silicon ring-resonators usually suffer from a trade-off between providing a high pair generation rate(PGR)and high extraction efficiency.To achieve high PGR,devices are generally operated with the signal and idler photons in the undercoupling regime and pump photons at the critical coupling point,while high extraction rates require the converted photons to be overcoupled.Therefore,the optimal conditions for achieving maximal output photon pair flux are critical coupling for the pump photons and overcoupling for the converted photons[2,3].

Coexistence of multiuser entanglement distribution and classical light in optical fiber network with a semiconductor chip

Building communication links among multiple users in a scalable and robust way is a key objective in achieving large-scale quantum networks.In a realistic scenario,noise from the coexisting classical light is inevitable and can ultimately disrupt the entanglement.The previous significant fully connected multiuser entanglement distribution experiments are conducted using dark fiber links,and there is no explicit relation between the entanglement degradations induced by classical noise and its error rate.Here,a semiconductor chip with a high figure-of-merit modal overlap is fabricated to directly generate broadband polarization entanglement.The monolithic source maintains the polarization entanglement fidelity of above 96%for 42 nm bandwidth,with a brightness of 1.2×10^(7)Hz mW^(−1).A continuously working quantum entanglement distribution are performed among three users coexisting with classical light.Under finite-key analysis,secure keys are established and images encryption are enabled as well as quantum secret sharing between users.This work paves the way for practical multiparty quantum communication with integrated photonic architecture compatible with real-world fiber optical communication network.