Defect Mode Passband Lasing in Self-Assembled Photonic Crystal

Abstract

Up to now colloidal photonic crystal (CPC) lasers essentially relied on photonic band gap edge effects, as a consequence of the poor passband quality achieved by previously reported engineering methods. In this paper, we demonstrate lasing oscillation in CPCs based on the defect mode passband effect. As defect mode, we introduce a highquality monolayer of silica spheres internally functionalized with laser dyes in a sandwiched CPC structure. This defect layer contains the gain medium for lasing action and at the same time breaks the translational symmetry of the crystal, resulting in a pronounced passband within the photonic band gap. The CPC acts as an optical resonator, effectively ensuring the feedback mechanism. The spectroscopic measurements and theoretical simulations match well and reveal that the relatively low-threshold lasing exhibited by the structure can uniquely be attributed to the efficient coupling of the spontaneous emission of the dye to the defect mode of the CPC. Our work provides a new promising strategy toward applications of functionalized self-assembled CPCs with a planar defect in all-optical switching, optoelectronics, and energy-harvesting, and even in the future generation of electro-optical devices, such as lab-on-a-chip with allintegrated optical spectroscopy techniques.

Strong Light–Matter Coupling as a New Tool for Molecular and Material Engineering: Quantum Approach

“…The influence on the emission intensity and the emission rate of an inserted molecular fluorophore is clearly there, as has been witnessed by enhanced energy transfer from a donor molecule with its emission suppressed in the bandgap; and by spectral narrowing of the emission suppressed by the broad forbidden stopband, yet enhanced in the allowed passband. But as a token of the relatively small effects, the spectral narrowing, as a necessary, yet not sufficient, condition for lasing, did not result in lasing in the photonic heterostructure . Also quantitatively, the decrease in emission rate was small (3–4 %), yet in good agreement with the calculated LDOS.…”

A Thin‐Film Flexible Defect‐Mode Laser

“…An alternative device configuration that circumvents the potential issue of photo‐bleaching of the gain medium when the CLC is photopolymerized is the defect‐mode structure 8–12. In this configuration a separate layer is formed for the gain medium that is sandwiched between two CLC layers ( Figure ).…”

Nonreciprocal Localization of Photons

“…Insertion of a defect in the periodic systems generates a high Q resonant mode in the gap which leads to spatial localization of wave functions in the vicinity of the defect 16,17 . The high Q modes are good candidates for designing photonic crystal lasers [5][6][7]18 .Embedding a pumped gain medium as a non-Hermitian defect in the photonic crystal results in the concentration and amplification of the light until it reaches to the threshold and starts to lase. Recent advancement in the non-Hermitian systems extended the concept of the photonic crystals to a new direction.…”

“…In photonics, localized states are extensively used to confine and manipulate photons [5][6][7][8][9][10][11] . Up to now, all the proposed localized states are reciprocal and restricted by time reversal symmetry.…”

“…Insertion of a defect in the periodic systems generates a high Q resonant mode in the gap which leads to spatial localization of wave functions in the vicinity of the defect 16,17 . The high Q modes are good candidates for designing photonic crystal lasers [5][6][7]18 .…”