文档介绍：电子信息科学与技术葛浩 200800800040 Using Microcontroller to Optimize the Bias Voltage of Balanced Photodiodes to Minimize Even-Order Distortion in Analog Fiber-Optic Links Abstract Use ofa microcontroller-based bias board for balanced photodiodes improves even-order distortion cancellation due to voltage dependent responsivity nonlinearities. The bias board improves the second order intermodulation distortion in balanced photodiodes by dB. K ey words: microcontroller e ven- o rder d istortion a nalog f iber- o ptic l inks Introduction Analog fiber optic links have been used for various applications from radio astronomy to antenna remoting [1,2]. The format of choice uses a quadrature-biased Mach-Zehnder modulator (MZM) for intensity modulation followed by direct detection ata receiver [3]. The quadrature-biased MZM is used because it adds no additional even-order distortion to the RF signal and the system performance metrics improve as the photocurrent increases. As the performance of these systems increases, the even-order distortion of the photodiodes es a limiting factor. The nonlinearity originates from the voltage dependent responsivity of the photodiode and has been studied [4]. In order to achieve the highest performance, links have been demonstrated using dual-output MZM with balanced photodiodes [5]. The balanced photodiodes can be arrayed so that each individual photodiode