采用两个对称相位发生器(PGC)同时取代两个传统3 dB耦合器，设计了一种新型宽光谱马赫曾德尔干涉仪(MZI)电光开关。利用给出的多元非线性最小均方优化算法，对PGC结构参数做了优化，补偿了由波长漂移造成的MZI电光区的模式相移漂移。在1550 nm中心波长下，所设计器件的电光区长度为5 mm，on和off状态下的驱动电压分别为0和±0.925 V。优化后器件的输出光谱可达250 nm (1430~1680 nm)，且在此光谱范围内，on状态的插入损耗小于5.91 dB，on和off状态间的消光比大于30 dB。在同等消光比水平要求下，该输出光谱范围约为传统MZI电光开关光谱范围(约为50 nm)的5倍，并近似为已报道的基于单个PGC非对称MZI电光开关光谱范围(约为85 nm)的3倍。所给出的宽光谱器件在光波分复用系统中任意波长信道的切换与路由方面具有较好的应用价值。

A novel improved wide-spectrum Mach-Zehnder interferometer (MZI) electro-optic (EO) switch is proposed by using two phase generating couplers (PGC) instead of two directional couplers (DC). With the proposed nonlinear least square optimization method, the PGC structure is optimized, and the phase-shift variation resulting from the wavelength variation is sufficiently compensated. Under the central wavelength of 1550 nm, the driving voltages of the designed switch are as low as about 0 (on state) and ±0.925 V (off state) with an EO region length of 5 mm. A wide spectrum more than 250 nm (1430~1680 nm) is achieved, and within this wavelength range, the insertion loss under on state is less than 5.91 dB, and the extinction ratio between on state and off state is larger than 30 dB. Under the same extinction ratio level, the output spectrum of this device is about 5 times of that of the traditional MZI EO switch with two 3 dB DC (about 50 nm), and is nearly 3 times of that of our previous reported asymmetric MZI EO switch using only one PGC (about 85 nm). The proposed wide-spectrum device structure exhibits potential wide applications in optical exchange and optical routing in wavelength division multiplexing systems.