High-order nonlinear optical response of a polymer nanocomposite film incorporating semiconducotor CdSe quantum dots

Xiangming Liu,Yusuke Adachi,Takuya Nakashima,Tsuyoshi Kawai,Juro Oshima,Yasuo Tomita

doi:10.1364/oe.20.013457

Abstract

We report on observation of high-order optical nonlinearities in our recently developed photopolymerizable semiconductor CdSe quantum dot (QD)-polymer nanocomposite films at various volume fractions of CdSe QDs as high as 0.91 vol.% (3.6 wt.%). We performed Z-scan and degenerate multi-wave mixing (DMWM) measurements using a 532-nm picosecond laser delivering single 35 ps pulses at a repetition rate of 10 Hz. Using the uniformly cured polymer nanocomposite films, we observed the third- and fifth-order nonlinear optical effects in closed-aperture Z-scan measurements by which it was found that saturable nonlinear absorption (light-induced transparency) and large negative nonlinear refraction were induced. We also measured dependences of the effective third- and fifth-order nonlinear refraction constants on CdSe QD volume fraction. Based on the Maxwell-Garnett model, we estimated the third- and fifth-order nonlinear optical susceptibilities of CdSe QD and discussed a contribution of the third-order effect to the fifth-order one due to the cascaded (local-field) effect. Coexistence of the third- and fifth-order nonlinear refraction was also confirmed by DMWM.

Highlights

We have developed a new polymer nanocomposite material system, the so-called photopolymerizable nanoparticle-polymer composites, where either inorganic-oxide or organic nanoparticles are uniformly dispersed in photopolymerizable monomer hosts [1]
In this paper we report on an observation of high-order optical response of photopolymerizable semiconductor CdSe quantum dot (QD)-polymer nanocomposite films in the Z-scan [49] and degenerate multi-wave mixing (DMWM) [26] measurements with a 532-nm picosecond laser at a low repetition rate
We have studied the nonlinear optical properties of uniformly cured semiconductor CdSe QDpolymer nanocomposite films by means of the Z-scan technique and DMWM with a 532-nm picosecond laser at a low repetition rate

Summary

Introduction

We have developed a new polymer nanocomposite material system, the so-called photopolymerizable nanoparticle-polymer composites, where either inorganic-oxide or organic nanoparticles are uniformly dispersed in photopolymerizable monomer hosts [1]. Over the past two decades intensive studies have been done to investigate optical nonlinearities in various semiconductor QDs such as CdSe [15,16,17,18,19,20,21,22,23,24,25], CdSxSe1-x [26,27,28,29,30,31,32], CdS [33, 34], CdTe [35,36,37], GaAs [38] and PbS [39, 40] that were uniformly dispersed in either liquid or solid hosts. Coexistence of the third- and fifth-order optical nonlinearities is examined by the DMWM measurement

Sample preparation

Experimental method

Open-aperture Z-scan

Closed-aperture Z-scan

Degenerate multi-wave mixing

Conclusions