Research Into Photodetectors Based On Novel High-Contrast Sub-Wavelength Grating

With the widespread use of photodetectors in optical communication systems,imaging systems and military fields,photodetectors are developing in the direction of high performance and high integration.In high-speed optical fiber communications,the requirements for photodetectors with high response bandwidth and high quantum efficiency are increasing.For the traditional vertical PIN photodetector,the mutual restriction between high quantum efficiency and high response bandwidth limits its application in high-speed fiber communication.Therefore,the new structure of the resonant cavity-enhanced photodetector(Resonant Cavity-enhanced Photodetector,RCE)was developed.High Contrast Subwavelength Grating(HCSG)is simple in structure,easy to prepare,and has good light field control characteristics.Therefore,optical devices integrated with subwavelength gratings have developed rapidly,and photodetectors based on subwavelength gratings are also available.Be concerned.This paper focuses on the research on the optical field control characteristics of the novel high-contrast sub-wavelength grating.First,introduce the theoretical method of analyzing high-contrast sub-wavelength.Secondly,based on the high reflection,high transmission,reflection convergence and polarization characteristics of the novel high-contrast sub-wavelength grating,a resonant cavity-enhanced photodetector integrating periodic and non-periodic novel high-contrast sub-wavelength gratings is designed.Finally,the designed grating is simulated and analyzed,and the quantum efficiency and response bandwidth of the overall device are simulated and tested.The main research content and research results of this paper are as follows:1.Propose a novel type of HCSG,which uses partially wet-oxidized Al₂O₃ as the low refractive index substrate of the sub-wavelength grating to form a high-contrast sub-wavelength grating.The characteristics of the novel periodic and aperiodic HCSGs,such as polarization insensitivity,polarization selection,high reflection,high transmission,and reflection convergence,are designed and simulated.2.Integrate the novel periodic HCSG on the PIN light detection structure to form an RCE photodetector.The novel periodic HCSG in the 850nm band realizes polarizatio insensitivityand high reflection characteristics,and the polarized light reflectivity of the two modes is above 98%.At the bottom of the device,13 pairs of Ga As/Al_0.9Ga_0.1As DBR mirrors are used,and the reflectivity of incident light in the 850nm band is above 98%.The quantum efficiency of the overall device reaches 69.6%,and the full width at half maximum is close to 0.1nm.The response bandwidth of the experimental test device is10.5GHz.3.The novel aperiodic HCSG is integrated on the PIN light detection structure to form an RCE photodetector.The novel aperiodic HCSG at the top realizes the high reflection and convergence characteristics of TM mode polarized light in the 850nm band,and the reflectivity reaches 86.5%and 1.5?m.The beam converges at the focal length.The bottom periodic Ga As grating achieves polarization selection characteristics for incident light.The polarized light transmittance of the TM mode is 96.1%,and the polarized light transmittance of the TE mode is only 3.7%.The quantum efficiency of the overall device has reached 71.8%,and the full width at half maximum is close to 0.1nm.