| Terahertz waves refer to electromagnetic waves with frequencies in the range of 0.1～10THz,located between microwaves and infrared.According to domestic and foreign researchThe investigation of the status quo and the preparation of terahertz detectors with high sensitivity,high response rate,low cost,light weight and mass production are still important research topics today.With the rapid development and application of terahertz waves,terahertz detectors have also been developed rapidly.For the design of terahertz detectors,studies have shown that the performance of pyroelectric materials and the adiabatic structure of the device are the main factors affecting the pyroelectric The main factor of infrared detector performance.This paper mainly studies the preparation of pyroelectric terahertz detectors based on pyroelectric thin film materials,and focuses on the overall device design of pyroelectric terahertz detectors based on lithium tantalate thin film materials.LiTaO3 single crystal material has It is the most commonly used pyroelectric material due to its large pyroelectric coefficient,high Curie temperature and small dielectric constant.Since the output signal of the sensitive element of the pyroelectric terahertz detector is a weak and small signal,the device has high requirements on the signal processing circuit.Based on the requirements for the device mentioned above,this paper designs and analyzes the signal readout circuit of the terahertz detector.The design includes the design of the terahertz first-level current amplifier circuit,the second-level voltage amplifier circuit and the filter circuit,and the simulation of each part of the circuit is carried out.This paper innovatively proposes a fourth-order band-pass filter circuit to process the output signal of the terahertz detector.The output signal of the sensitive element of the terahertz detector is a weak and small current signal in the order of pA～nA.The amplification of the amplifier circuit module and the secondary modulation module,the signal processing is the amplified voltage signal,but considering the effective suppression of noise,this design selects a fourth-order band-pass filter,which can effectively suppress noise and improve the signal-tonoise ratio.1.The microscopic analysis and performance characterization of the lithium tantalate film were analyzed,and the crystallinity of the film material,the surface morphology of the film and the pyroelectric properties of the lithium tantalate film were studied and tested.2.The detector structure composed of LiTaO3 thin film and silicon substrate with grooves is designed,and the thermal simulation of the detector structure is carried out by finite element simulation.The fabrication process of the sensing element of the terahertz detector based on LiTaO3 film was designed,the prototype device of the detector was fabricated,and the device structure and integration process were preliminarily verified.3.The signal processing circuit of the detector is designed.Since the output signal of the sensitive element of the terahertz detector is a weak and small signal,the signal processing circuit of the detector is designed and analyzed,and the overall structure of the signal processing circuit is constructed,including the preamplifier circuit,Analysis and design of secondary modulation circuits and filters. |
