基于MMI滤波器的可调谐连续光全光纤OPO

在连续光全光纤光学参量振荡器（FOPO）中，目前主要利用可调滤波器（TBPF）等高插入损耗的滤波器件进行边带光输出波长的调谐，这种方式所引起的高环形腔损耗限制了FOPO输出性能的进一步提升。为解决此问题，提出了基于多模干涉（MMI）滤波器的低腔损耗可调谐连续光FOPO。通过选取不同长度和纤芯尺寸的多模光纤制作级联单模-多模-单模光纤（SMS）作为滤波器件，使其在选定波长处的插入损耗小于1 dB，FOPO环形腔的总损耗不大于5 dB，并通过对SMS器件施加轴向拉力的方式调节滤波器件的透射谱，实现了1 494~1 501 nm和1 638~1 629 nm范围内的双边带可调谐连续光输出。

Tunable CW all-fiber optical parametric oscillator based on the multimode interference filter

High insertion loss filter components like tunable bandpass filters(TBPF) are commonly used to tune the sideband output wavelengths in continuous-wave(CW) all-fiber optical parametric oscillators (FOPO). Aiming at reducing the high ring-cavity loss mainly caused by the insertion-loss of the bandpass filter, a low cavity-loss tunable CW FOPO based on multimode interference(MMI) filter was proposed. Cascaded single-mode-multimode-single-mode(SMS) fiber devices were fabricated as filter devices by selecting multimode fibers with different lengths and core-sizes. And their insertion-losses at selected wavelengths were less than 1 dB, and the total losses of the FOPO ring cavity were not more than 5 dB. By applying an axial pulling force to the SMS device to adjust the transmission spectrum of the filter device, the double-sideband output wavelengths could be tunable in the range of 1 494-1 501 nm and 1 638-1 629 nm.