| Quantum light source is the core device in the field of quantum information science and technology,which are widely used in quantum computing network,quantum secure communication,quantum precision measurement and other fields.As quantum information technology moves towards scalability and practicality,there is an increasingly urgent demand for complex entangled states with high dimensions/multiple photons,making the development of frequency-domain multi-mode quantum light sources crucial.Additionally,integration and miniaturization of quantum entangled light sources is also an important research direction.Therefore,exploring the preparation of high-quality integrated quantum light sources based on different material platforms is essential for advancing quantum information technology.Gallium nitride(GaN)materials have excellent nonlinear optical properties and mature processing technology,making them potential for preparing high-quality quantum light source.This thesis proposes and prepares a quantum light source based on a gallium nitride micro-ring resonator,and studies its single photon and entanglement properties.The specific research content is as follows:(1)The basic theory of micro-ring and the generation mechanism of correlated photon pairs in micro-ring were analyzed.The key parameters of the microring resonator were introduced in detail,the transmission and dispersion characteristics of GaN microring resonators were theoretically analyzed,clarifying the mechanism by which correlated photon pairs are generated through spontaneous four-wave mixing processes in micro-ring resonators.(2)Design,fabrication and characterization of GaN micro-ring devices.The characteristics of GaN materials were described in detail,and undoped GaN thin films were grown on sapphire substrates through external collaboration,with a quality factor of～106 and a free spectral range of～330 GHz obtained for GaN micro-rings.Finite element simulation and experimental testing of the dispersion of micro-rings were carried out to obtain a wide-spectrum anomalous zero-dispersion curve with a dispersion coefficient of-8.26 × 10-27 s2/m.The simulation results are in agreement with the experiment.(3)The correlation characteristics,single-photon characteristics and energy-time entanglement characteristics of a Gallium Nitride micro-ring frequency-domain multimode quantum light source were studied.A quantum light source experimental platform based on GaN micro-ring resonator was constructed,and the spectral distribution of the quantum light source was measured,and a quantum frequency comb was generated within a range of 80 nm.Joint spectral intensity measurements were performed on 7 pairs of photons.At a pump power of 1.83 mW,a count rate of 345 kHz was detected for the idler photons,and the maximum value of the coincidence-toaccidental ratio(CAR)was 243±24.The performance of the light source as a singlephoton source was studied,and the second-order autocorrelation function g(2)(0)for the photon single-mode thermal field was 1.9983±0.0384.For the heralded singlephoton source,the conditional second-order autocorrelation function gH(2)(0)for the photon was 0.045±0.001 at a heralding signal photon rate of 189 kHz.The characteristics of the light source as an entangled light source were also studied.The energy-time entanglement characteristics were verified by a two-photon interference experiment,and the interference fringe visibility was 99.74±3.43%.This is the first time to demonstrate the quantum correlated/entangled photons generation based on GaN microring device.The results show that GaN microring devices have the potential to develop high-quality quantum light sources,which provides a new idea for the fully integrated quantum optics platform. |
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