Vertical-Cavity Surface-Emitting Laser With Cholesteric Liquid Crystal Overlay

Author

Panajotov, K. ; Dems, M. ; Belmonte, Carmine ; Thienpont, Hugo ; Yi Xie ; Beeckman, Jeroen ; Neyts, Kristiaan

Author_Institution

Dept. of Appl. Phys. & Photonics (B-PHOT TONA), Vrije Univ. Brussel, Brussels, Belgium

Volume

32

Issue

1

fYear

2014

fDate

Jan.1, 2014

Firstpage

20

Lastpage

26

Abstract

We study theoretically the spectral and polarization threshold characteristics of vertical-cavity surface-emitting lasers with an overlay of cholesteric liquid crystal (CLC-VCSELs). Due to the existence of CLC band gap for circularly polarized (CP) light the polarization state of the resonant modes in the compound system evolves from linear (LP) inside the VCSEL to elliptical and circular (CP) inside the CLC. As a result, the output mirror reflectivity is increased and CLC-VCSEL threshold gain is decreased. We elucidate the transition from LP to CP state of the generated light by studying the role of the CLC thickness and the top distributed Bragg reflector reflectivity. This transition takes place for 5-6 μm thick CLC and is not gradual but happens in an oscillatory fashion. When the CLC thickness is fixed and the VCSEL top mirror reflectivity is decreased a profound gradual red shift of the resonant mode wavelength and increase of threshold gain are observed.

Keywords

cholesteric liquid crystals; distributed Bragg reflector lasers; laser mirrors; light polarisation; red shift; reflectivity; surface emitting lasers; CLC band gap; CLC-VCSEL threshold gain; VCSEL top mirror reflectivity; cholesteric liquid crystal overlay; circularly polarized light; distributed Bragg reflector reflectivity; polarization threshold characteristics; red shift; resonant modes; vertical cavity surface emitting laser; wavelength 5 mum to 6 mum; Color; Distributed Bragg reflectors; Indexes; Optical polarization; Polarization; Vertical cavity surface emitting lasers; Cholesteric liquid crystals (CLCs); light polarization; liquid crystals (LCs); vertical-cavity surface-emitting lasers (VCSELs);

fLanguage

English

Journal_Title

Lightwave Technology, Journal of

Publisher

ieee

ISSN

0733-8724

Type

jour

DOI

10.1109/JLT.2013.2288996

Filename

6655934