Single-Photon Imaging Based On Near-Infrared Spectrum-encoded Dual-comb Interferometry

In order to accurately measure the smallest unit of light——single photons,singlephoton detection technology was born,which is one of the most precise detection techniques in the field of optics and becoming a hot topic of current research.In recent years,the proliferation of single-photon applications,such as bosonic sampling quantum computing,waveguide optical quantum chips,quantum key distribution and single-photon cameras,has greatly promoted the development of the single-photon techniques,and also put forward higher requirements on the detection capability of photons.Single-photon detection technology advances faster and higher in terms of detection time and detection efficiency,and has a wide range of applications in quantum information,single photon Li DAR,environmental monitoring,optical communication,biofluorescence detection,etc.As an important application of single-photon detection technology,single-photon imaging technology uses photon-level measurements to achieve the presentation of macroscopic images.As an important symbol of traditional optics transferring to photonics,single-photon imaging is a product of interfusion of multiple disciplines and research fields.Single-photon imaging combines time-correlated single-photon counting technology with high temporal accuracy and single-photon detection technology,which has the advantages of high detection sensitivity,high temporal resolution,super-resolution imaging,low-dimensional detector to obtain highdimensional image information,and strong anti-interference capability.Single-photon imaging is flourishing as a new generation of optical imaging technology,and has a wide range of applications in many frontier science and technology fields such as aerospace remote sensing,biomedical diagnosis,national defense and military,civil manufacturing,and astronomical detection.This thesis will focus on the theme of “Single-Photon Detection and Imaging Applications in Communication Wavelengths”.The dual-comb interferometry and spectral coding technology was introduced into the field of single-photon imaging,realizing dual-comb interferometry spectrum-encoded imaging at the photon-counting level.And broadband single-photon frequency upconversion detection was realized by using a time-frequency domain precision-controlled frequency upconversion technology.The specific research contents and innovations are summarized as follows:1.Application of dual-comb interferometry spectrum-encoded imaging technique to two-dimensional imaging of photon counting levels,realizing photon imaging based on spectrum-encoded dual-comb interferometry.The dual optical comb interferometric spectral encoding imaging technique encodes the position information of the spatial target and the spectral components of the optical comb,and performs line scanning in only one dimension,which reduces the scanning dimension of single-pixel detector two-dimensional imaging and improves the imaging efficiency.In this imaging system,the target surface reflectance and spatial position information can be obtained by using only a single pixel detector without spatial resolution capability.In the optical path design,the echo signal and incident light share the same optical path,which reduces the complexity of the system and improves the overall stability of the system.2.A precision measurement technique for single-photon level dual-comb spectroscopy with controllable resolution has been proposed,realizing highly sensitive and rapid measurement of photon-counting level dual-comb spectroscopy.The measurement of optical signal spectra at the photon counting level in the communication band is realized by using the single-photon detection technique combined with the time-correlated single-photon counting technique and the dualcomb spectroscopy technique.The effect of precision manipulation of the frequency-domain dual-comb interferometry spectral resolution was achieved by using an arbitrary signal generator to adjust the time window of the time-correlated single-photon counter.The time window length was adjusted from 2 μs to 100 μs,and the results of different time windows were compared,and it was finally determined that the best spectral resolution was achieved when the time window was set at 16 μs in this imaging system..3.The broadband single-photon frequency upconversion detection technique in the communication band is verified by experiments.A pulsed laser with a central wavelength of 1563 nm,a linewidth of 8 nm,and a pulse width of 0.85 ps is used as the signal light,and a pulsed laser with a central wavelength of 1036 nm,a linewidth of 18 nm,and a pulse width of 35 ps is used as the pump light,and a periodically polarized lithium niobate crystal with a crystal temperature of 103 °C is used as the nonlinear medium to generate 623 nm visible photons for detection using Si-APD.The precision-controlled cross-phase modulation all-optical synchronization technique in the time-frequency domain with broadband pumping and temperature tuning methods are applied to improve the quantum efficiency of broadband single-photon frequency upconversion and the overall detection efficiency of the system.The high-precision synchronization of the signal light and pump light in the time domain controls the noise within a narrow time window of the pump pulse,and combines with an efficient filtering system to effectively remove the noise introduced by the strong pump light and environment.A highefficiency,low-noise broadband single-photon frequency upconversion detection is achieved,and the conversion efficiency of the system is 19.8%,with a corresponding background noise of 15 kcps.