Affiliation:
1. School of Physics and Optoelectronic Engineering, Institute of Information Photonics Technology,
Beijing University of Technology, Beijing 100124, P. R. China.
Abstract
Phase control of random lasing processes has been a challenge both in physics and in the device/materials design. Although conventional saturable absorbers can be integrated with random lasers to conceive mode-locking scheme, low intensity and random directions of the lasing radiation reduce largely the possibility. In such considerations, we put forth a new mode-locking mechanism, which is defined as cascaded absorption and stimulated emission (CASE), and have it achieved in multicrystalline microdisk structures of a hybrid perovskite. This scheme applies only to lasing materials with strong overlap between the absorption and emission spectra. In this work, we employed 2-photon pumping at 800 nm with a pulse duration of about 150 fs to realize phase-locked random lasing in MAPbBr
3
microdisks in donut shapes, which are produced by micro-imprinting using a flexibly transferred template of tricyclo[5.2.1.0
2,6
] decanedimethanol diacrylate. The phase-locking performance is identified by the narrow-band lasing lines with equal separations. The constant phase shift for initializing phase locking is determined by the internal conversion lifetime in the MAPbBr
3
molecules. Two-photon pumping enables large penetration depth into the microdisks and consequently large numbers of phase-locked lasing modes, producing much narrowed and high-contrasted spectral lines. Lasing lines with a bandwidth as narrow as 0.26 to 0.3 nm and an equal separation ranging from 1.7 to 4.8 nm have been achieved for different microdisk schemes. These results imply marked progress in new random lasing physics and potential applications in ultrafast laser technology.
Funder
National Natural Science Foundation of China
Publisher
American Association for the Advancement of Science (AAAS)