Frontier technology of infrared photodetector $ Avalanche amplified infrared single photon detector manipulated by optical field
2021, 50(1): 20211002.
doi: 10.3788/IRLA20211002
The thin layer of infrared detection material guarantees the uniformity of the materials and reduces the signal noise in infrared detection. The absorption of infrared detector is limited by the thin layer of infrared detection material attributing to small volume. According to the characteristics of different infrared detection materials, artificial microstructure can effectively improve the performance of infrared detector. The strategies of enhancing the absorption of thin-layer infrared detection materials were introduced. The strategies were based on metal back plate, metal grating and asymmetric Fabry-Perot cavity. They could have an excellent performance in their own adaptive scenarios. Meanwhile, the mechanism of adjusting the absorption peak height and width by artificial microstructure was also elaborated briefly. The application of artificial microstructure in several infrared detectors was demonstrated. Finally, an artificial microstructure HgCdTe infrared detector was designed, which could achieve broadband absorption in 3.5-5.5 μm atmospheric window. The absorption peak reached 91.8% and the relative peak width was 41.8%. In most of frequency in the atmospheric window, the absorption enhancement is higher than 6. The development of artificial microstructure opens up the design idea of traditional infrared devices, and provides theoretical basis and guidance for new infrared devices.
2021, 50(1): 20211003.
doi: 10.3788/IRLA20211003
Metalenses are two-dimensional metasurfaces composed of sub-wavelength scatters with planar configuration and light focusing function. They can manipulate the amplitude, phase, dispersion and polarization of the light field at sub-wavelength spatial resolution, and develop rapidly in recent years. The subwavelength resonant nanostructure suppresses the high-order diffraction, and the incident light can be perfectly modulated to the predesigned diffraction order, thus ensuring the high efficiency of the metadevice for manipulating the photons. Besides, the design flexibility and specific electromagnetic response of the meta-unit enable metasurfaces to achieve customized control of the multiple dimensions of the light field. In contrast to the traditional refraction lens relying on the phase accumulation effect, the broadband achromatic metalens resolves the complex and bulky limitations of the traditional optical system caused by cascading multiple lenses to correct the chromatic aberration by independently and simultaneously manipulating the phase and phase dispersion of the optical field. It provides a promising way for the miniaturization of on-chip integrated photonics. Focusing on the progress of metalens, this review discussed the basic principles of metasurface on engineering the amplitude, phase and polarization state of the light firstly. Then the development of metalens in recent years was focused on, including the realization of single-wavelength metalens and the development of multi-functional broadband achromatic metalenses through manipulating the multiple parameters (polarization, phase and phase dispersion). Finally, the potential challenges and application prospects for further developing the metalenses were discussed.
2021, 50(1): 20211004.
doi: 10.3788/IRLA20211004
High-precision comparison of time-frequency is an important technology to achieve high-precision time-space consistency and time-frequency stability of the whole society information system, and provides a unified time guarantee for key areas of national economic development. Owing to its high detection efficiency, low noise, low timing jitter, and easy integration, silicon single photon detector is the key core chip in the high-precision satellite-to-ground time comparison system. The interrelationship between photon detection efficiency, dark count rate and timing jitter of the silicon single photon detector was analyzed in this paper. Based on the in-depth review of the research of the silicon single photon detector, the relationship between photon detection efficiency and timing jitter was effectively overcome. A silicon single photon detector with a photosensitive diameter of 200 μm, photon detection efficiency of 50% at room temperature, and the timing jitter of 46 ps was developed. Its application in the satellite-to-ground time comparison was briefly introduced finally.
2021, 50(1): 20211005.
doi: 10.3788/IRLA20211005
Metalens, the specific type of lens designed with the surfaces mading of two dimensional array at the subwavelength scale, has shown great flexibilities to control the light field, including the arbitrary modulation abilities of amplitude, phase and polarization at the subwavelength scale. Moreover, the metalens possesses the unique advantages of low loss, integratable and conformable design and ultrathin, therefore attracts immense attentions in recent years. However, in most cases, the metalens designed for a specific wavelength may penetrate through the large chromatic aberration, which limits their usefulness in multi-wavelength or broadband applications. On the other hand, the metalens has renewed new degrees of freedom due to its two-dimensional planar structure, which has the potential in the elimination of chromatic aberration. Some different typical achromatic metalens designs and their achromatic modulation mechanism were reviewed, the existing achromatic metalens were classified from the types of modulated light bands, such as the achromatic matelens for discrete and continuous wavelength respectively, and the latter can be classified as transmissive and reflective from the working mode. Finally, the application of metalenses array in imaging and their prospect of broadband achromatic devices of large depth of field were introduced.
