[OPTICAL REVIEW Vol. 17, No. 3 (2010) 300-304]
© 2010 The Japan Society of Applied Physics

Effect of Particle Size and Shape on Nonresonant Random Laser Action of Dye-Doped Polymer Random Media

Takashi OKAMOTO* and Shiro ADACHI

Department of Systems Design and Informatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502, Japan

(Received September 18, 2009; Accepted March 1, 2010)

We present an experimental study of the light emission from dye-doped polymer random media dispersed with TiO2 particles of various sizes, shapes, and structures. Random lasing with nonresonant feedback, similar to that for spherically shaped particles that are used for conventional random lasers, is observed for almost all types of particles and aggregates. The efficiency of random lasing for each medium is analyzed using the relationship between the emission spectrum and the transport mean free path (TMFP), which is measured by enhanced backscattering experiments. Results show that the peak emission intensity depends strongly on the particle shape and structure, whereas the spectral linewidth is governed by the TMFP.

Key words: random laser, gain media, photopolymer, multiple scattering, particles, aggregates

*E-mail address: okamoto@ces.kyutech.ac.jp