Reserce On Homodyne Detector Of Weak Optical Signal

With the rapid development of optical fiber communication technology and semiconductor photosensitive devices,the application of photoelectric detection technology goes deep into all aspects of production and life.There are two methods of photoelectric detection:direct detection and coherent detection.Coherent detection is often used in the field of weak optical signal detection where includes laser communication,speed and distance by radar mea.surement,heterodyne spectroscopy,laser gyroscope and infr-ared physics.Coherent detection can be divided into heterodyne detection and homodyne detection.Among them.homodyne detection is a powerful tool for measuring the field quadrature of an electromagnetic mode and the homodyne detector is often used in inon-classical optical field,such as optical homodyne tomography,compressed state detection and coherent state detection.This paper mainly studies the homodyne detection technology and the design and implementation of a homodyne detector.First of all,the paper introduces the principle of homodyne detection and the circuit structure of a homodyne detector,the noise components and noise reduction schemes of a homodyne detector.Then,we design and implement two kinds of homodyne detectors,and analyze the criteria of chip selection,circuit schematic diagram and PCB design problems in the process of realizing a homodyne detector.Then,the paper analyzes and tests several parameters of the homodyne detector,summarizes the performance parameters of the two homodyne detectors and points out its advantages and disadvantages.Finally,the improvement scheme of the homodyne detector is proposed.At present,for the homodyne detector reported by scientific research institutions,some parameters such as the quantum to classical noise ratio,bandwidth,etc.are not balanced well.However,the two balanced homodyne detectors in this paper,not only ensure that these parameters reach a high level at the same time,but also have had a breakthrough in both the quantum to classical noise and bandwidth.These two homodyne detectors have the following performance metrics:?.5MHz homodyne detector adopts transimpedance operational amplifier chip scheme with high gain bandwidth product.By designing two-stage amplifier circuit structure,the actual bandwidth of the homodyne detector reaches 6MHz,RMS noise is 3.6mV,the gain is 121.6dB,the quantum to classical noise ratio at any frequency point of 0-5MHz is greater than 27.85dB when optical power is 1.78mW,and the common mode rej ection ratio is 40.78dB at 5MHz.?.The 1.2GHz homodyne detector adopts a large bandwidth RF operational amplifier chip scheme.By designing a two-stage amplifier circuit structure,the actual bandwidth of the homodyne detector reaches 1.2GHz,the RMS noise is 3.08mV,the gain is 73.7dB,the quantum to classical noise ratio reaches 18dB w-hen the optical power is 8mW,and the common mode rej ection ratio is 57.9dB at 50MHz.The above two homodyne detectors have reached the target set by this paper.The quantum to classical noise ratio of 5MHz homodyne detector and the bandwidth of 1.2GHz homodyne detector have reached the leading level,which satisfies the requirements of homodyne system for homodyne detector very well.