【摘要】 高频超声波在紫外写入的光纤布拉格光栅(FBG)上传播,产生的长周期超声光栅调制光纤光栅,形成光纤超声超结构光栅。利用模式耦合理论,分析了光纤超声超结构光栅的光谱特性,得出光纤超声超结构光栅的反射谱存在多个反射峰,其反射峰的波长间隔由超声波的频率决定。因此,可以通过改变超声波的频率,调节一阶反射谱的反射波长,从而实现宽调谐范围的快速波长可调滤波器。该滤波器与通常的声光可调滤波器相比,带宽更窄,调谐速度更快。更多还原

【Abstract】 The high frequency ultrasonic wave transmitting along UV-induced fiber Bragg grating, produces a long periodic ultrasonic grating to modulate the fiber Bragg grating, which is called as ultrasonic superstructure fiber grating. The acoustic-optic characteristics of the ultrasonic superstructure fiber grating are analyzed by using mode coupling theory. It is found that there are many individual peaks with same interval in the reflective spectra of ultrasonic superstructure fiber grating, and the interval of reflective peaks depends on the ultrasonic frequency. It is therefore possible to tune the reflective wavelength of first-order peak in the reflective spectra through changing ultrasonic frequency, so as to realize fast-tunable acoustic-optic filter with wide tunable range. Compared with conventional tunable acoustic-optic filters the present filter offers more narrow bandwidth and faster tuning speed.更多还原