title: Tunable Picosecond Laser Pulses via the Contrast of Two Reverse Saturable Absorption Phases in a Waveguide Platform.
abstract: How to enhance the optical nonlinearity of saturable absorption materials is an important question to improve the functionality of various applications ranging from the high power laser to photonic computational devices. We demonstrate the saturable absorption (SA) of VO2 film attributed to the large difference of optical nonlinearities between the two states of the phase-transition materials (VO2). Such VO2 film demonstrated significantly improved performance with saturation intensity higher than other existing ultrathin saturable absorbers by 3 orders due to its unique nonlinear optical mechanisms in the ultrafast phase change process. Owing to this feature, a Q-switched pulsed laser was fabricated in a waveguide platform, which is the first time to achieve picosecond pulse duration and maintain high peak power. Furthermore, the emission of this VO2 waveguide laser can be flexibly switched between the continuous-wave (CW) and pulsed operation regimes by tuning the temperature of the VO2 film, which enables VO2-based miniature laser devices with unique and versatile functions.
authors.affiliation: School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Tan
authors.affiliation: NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, 117456, Singapore.
authors.forename: Lianwei
authors.initials: L
authors.lastname: Chen
authors.affiliation: School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.affiliation: School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
authors.forename: Yanxue
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Dresden, 01314, Germany.
authors.forename: Shavkat
authors.initials: S
authors.lastname: Akhmadaliev
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Dresden, 01314, Germany.
authors.forename: Shengqiang
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore.
authors.forename: Minghui
authors.initials: M
authors.lastname: Hong
authors.affiliation: School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Chen