Emission Direction‐Tunable Liquid Crystal Laser. Issue 16 (25th May 2020)

• Record Type: Journal Article
• Authors: Cho, SeongYong; Yoshida, Hiroyuki; Ozaki, Masanori
• Is Part Of: Advanced optical materials. Volume 8:Issue 16(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-05-25
• Subjects: cholesteric liquid crystals -- direction‐tunable lasers -- photoalignment -- photonic crystals; Optical materials -- Periodicals; Photonics -- Periodicals; 620.11295
• DOI: 10.1002/adom.202000375
• Languages: English
• ISSNs: 2195-1071

Abstract

Abstract: Photonic crystal lasers possessing tailored lasing characteristics have attracted significant attention for various applications such as holography, optical communications, and LiDARs. Liquid‐crystal‐based photonic crystals are actively investigated to realize tunable lasers capable of controlling the emission wavelength, but it is a challenge to realize lasers with the capability to tune the emission direction. Here, a photonic band‐edge laser with tunable output direction is reported based on an engineered cholesteric liquid crystal with a slanted helical structure. In addition to the modulation of the director along the helical axis of the liquid crystal, a fine‐pitch modulation is introduced in the direction perpendicular to the helical axis, so that the photonic band‐edge is shifted away from the helical axis. By doping a dye in the liquid crystal, a microlaser that emits at an angle of ≈30° to the surface normal is realized. Further, control of the emission angle is achieved by modulating the periodicity of the photonic structure by an external stimulus. This work shows that organic microlasers with inexpensive fabrication methods can be engineered to possess advanced functionality such as beam‐scanning. Abstract : A direction‐tunable laser is achieved using a slanted cholesteric liquid crystal. In addition to the helical periodicity, a new periodicity is introduced in the lateral direction by photoalignment, causing the emission to become off‐axis. This work shows that liquid crystal lasers are capable of not only changing their wavelength, but their emission direction.