Supporting Information for
Free-standing membrane polymer laser on the end of
an optical fiber
Tianrui Zhai*,1, Li Chen2, Songtao Li1, Yujie Hu1, Yimeng Wang1, Li Wang1, and
Xinping Zhang*,1
1
Institute of Information Photonics Technology and College of Applied Sciences, Beijing
University of Technology, Beijing 100124, China
2
Department of Mathematics & Physics, North China Electric Power University, Hebei
071000, China
*Corresponding authors: trzhai@bjut.edu.cn and zhangxinping@bjut.edu.cn
Table of Contents
1. Confinement mechanism of the free-standing membrane structure ................................... 2
2. Measurement of the emission fans of the polymer laser ..................................................... 2
Reference .................................................................................................................................. 3
1. Confinement mechanism of the free-standing membrane structure
Figure S1 presents the schematic of the confinement mechanism of the waveguide
structure with and without a substrate. It can be seen that the refractive index difference
between the membrane (~1.7) and air (~1.0) is bigger than that between the membrane
and the ITO layer (~1.6). Thus, some radiation leaks out into the substrate as shown in
Fig. S1(a). However, for the free-standing polymer membrane structure in Fig. S1(b),
most radiation is effectively confined within the polymer waveguide (membrane) due
to the strong reflection at the two membrane/air interfaces.
Therefore, strong confinement of the radiation can be achieved by employing the
free-standing membrane structure without a substrate as shown in Fig. S1(b).
Fig. S1. Schematic of the confinement mechanism of the waveguide structure (a) with and (b)
without a substrate. The black arrows denote the propagation of the radiation.
2. Measurement of the emission fans of the polymer laser
An optical fiber collimating lens with a diameter of 5 mm is used to collect the
laser emission, which is mounted on the fiber tip as shown in the inset in Fig. S1(a).
The emission spectra shown in Figs. 3(i) and 3(j) can be obtained by placing the fiber
1 in Fig. S1(a).
on the site ○
Fig. S2. (a) Photographs of laser spots from an operating polymer laser. (b) Emission spectra
1 , ○
2 , and ○
3 in (a)) of the laser spot. The inset shows
measurements on three different sites (○
the optical fiber with a collimating lens.
The measured emission spectra are demonstrated in Fig. S2(b) when the fiber is
1 , ○
2 , or ○
3 ). Note that the relative intensity and the
moved to a different position (○
wavelength change for different positions, which has been reported as "emission fans".1
Reference
1
S. Riechel, C. Kallinger, U. Lemmer, J. Feldmann, A. Gombert, V. Wittwer, and U. Scherf, Appl.
Phys. Lett. 77, 2310-2312 (2000).