利用二氧化钒(VO2)的饱和吸收性质, 通过消逝场吸收的方式对波导激光进行调节, 实现了皮秒脉冲激光输出; 通过控制VO2的温度可对输出激光的脉冲宽度、重复频率和能量等进行调控。在VO2薄膜从绝缘相过渡到金属相期间, 通过测量复合光波导(掺杂钇铝石榴石波导表面附着VO2)的激光输出, 可直接观察到VO2的可饱和吸收性质。VO2薄膜与波导模式这两者之间通过消逝场相互作用, 使得VO2对光的吸收显著增加。受益于VO2独特的热驱动光学性质, 在1064 nm处, 波导激光在皮秒脉冲和连续波机制间可有效切换。由于VO2薄膜可饱和吸收的热滞特征, 通过冷却或加热处理, 在相同的温度条件下, 复合波导可产生连续激光和皮秒脉冲激光。这项研究为在芯片级平台上实现热控制有源集成光源提供了一种方法。

Using the saturated absorption properties of vanadium dioxide (VO2), we achieve picosecond pulse laser output by adjusting waveguide laser via evanescent-field absorption mode. The pulse duration, repetition frequency and energy of output laser can be adjusted by controlling the temperature of VO2. VO2 membrane on neodymium-doped yttrium aluminum garnet (Nd∶YAG) waveguides can be used as the saturable absorber, whose saturable absorption is directly observed during the transition from the insulator to the metallic phase. Through the evanescent-field interaction of VO2 membrane with waveguide mode, the optical absorption of VO2 increases significantly. Benefiting from the unique thermal-driven optical properties of VO2, the waveguide lasing at 1064 nm exhibits effective switching of operation between the picosecond pulses and the continuous-wave (CW) regime. Due to the thermal hysteresis feature of the saturable absorption of VO2 membrane, the CW and picosecond pulse laser can be generated at the same temperature by either cooling or heating treatments. This work opens a way to achieve thermally controlled active integrated light sources in a chip-scale platform.