Electrically tunable lasers made from electro-optically active photonics band gap materials

Abstract

External cavity-free and electrically tunable laser made from photonics band gap (PBG) materials with electrically tunable stop band is reported. The tunable PBG materials are developed from a family of novel cholesteric liquid crystals (CLC) with electrically variable pitch that adopts a non-constant distribution in space across the CLC film. The CLC exhibits a distributed feedback cavity whose resonant frequency can be electrically varied over a spectral range wider than 300 nm. Under an optical pumping and subject to a variable electric field, a tunable laser has been demonstrated in experiment that shows a wavelength tuning over 33 nm.

Electrically Tunable Organic Distributed Feedback Lasers Embedding Nonlinear Optical Molecules

“…This result corresponds to a tunability coeffi cient of 0.17 nm/V, almost twice the best performances reported by other electrically-driven tunability concepts. [18][19][20][21][22] Lasing occurs in the low-energy tail of the gain peak, evidencing that the shift of the waveguide cutoff wavelength is responsible of the observed tunability. Upon tuning, we fi nd a slight increase of the lasing mode linewidth (inset of Figure 4 d), since the used grating is less effective in providing feedback when the emission peak blue-shifts.…”

“…[ 17 ] The basic idea of all these approaches is the variation of the DFB period ( Λ ) or of other geometric characteristics and, consequently, of the effective refractive index (n eff ), since the emission wavelength ( λ ) is given by the Bragg condition, m λ = 2 n eff Λ , where m is the diffraction order. Electrical tunability is reported in liquid crystal lasers, [18][19][20] by using a liquid crystal as cladding layer, [ 21 ] or an electroactive substrate. [ 22 ] Most of these methods allow continuous and reversible tuning of the emission wavelength within a range < 10 nm, whereas a remarkable tunability over 47 nm has been achieved in Ref.…”

Tunable and Memorable Optical Devices with One-Dimensional Photonic-Crystal/Liquid-Crystal Hybrid Structures

“…Among them, the PBG of CLCs depends on the LC and chiral parameters. The tunable CLC PCs can thus be realized by adjusting the external factors such as temperature (Morris et al, 2005;Hung et al, 2000), light irradiation (Bobrovsky et al, 2003;Lin et al, 2005), or electric field (Choi et al, 2009;Lin et al, 2005;Yu et al, 2005). Some other tunable PCs based on FLC (Kasano et al, 2003) or BP LC (Yokoyama et al, 2006) have also been demonstrated.…”

Effect of UV curing conditions on polymerized tunable chiral nematic liquid crystals

“…In addition direct control and tuning of the PBG are of crucial importance for several emerging applications such as switchable optical devices, lab-on-a-chip devices as sensors 9 , modulators, reflectors and diffraction gratings. External stimuli can be used to tune the PBG such as heat [10][11][12][13] , light [14][15][16] , elasticity 17 and voltage [18][19][20][21][22][23][24][25][26][27][28][29] . In previous work 30 switchable devices with tuneable PBG with a fast response to electrical addressing and tuning over a broad range of wavelengths are demonstrated with a high reproducibility without deformation and degradation (Figure1).…”