Spontaneous Emission Control in Micropillar Cavities Containing a Fluorescent Molecular Dye

Abstract

Microcavity micropillars are structures composed of two high-reflectivity distributed Bragg reflectors (DBRs) placed either side of an active dipole emitter. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] This structure is then vertically etched to form a pillar. The three-dimensional confinement of the optical field within a micropillar has profound effects on fundamental light-emission processes. The most important of these results from reduced-mode volume (termed the Purcell Effect [17] ), which can cause a significant enhancement in the spontaneous emission rate by up to five times. [1,2,16] Furthermore, micropillars can sustain a series of discrete laterally confined modes, [3,4,9,13,15] which show no dispersion. [15] This permits photons that are emitted (via a particular mode) to be collected with high efficiency. When a single quantum emitter is placed within a micropillar, an efficient source of anti-bunched single photons can be created. [10,11,16] Such light sources are anticipated to find applications in quantum-cryptography [18] and quantum-computation systems. [19,20] Micropillars are also an exciting tool for studying fundamental processes such as light-matter coupling. In particular, recent reports have demonstrated strong optical coupling between a single quantum dot (QD) within a micropillar and a discrete optical mode.[12] The resultant polariton states are anticipated to be of significant importance in the development of quantum-computation systems. [19] Until now, the only material systems used as the active dipole emitters in micropillars are inorganic semiconductors, such as InAs [9][10][11] and InGaAs [12] quantum dots or CdTe quantum wells. [13] There is, however, buoyant interest in the physics and applications of organic materials in photonics. Apart from simple one-dimensional planar organic cavities, [21][22][23][24][25][26][27] optical confinement has also been studied in a large range of different structures containing active organic chromophores.These include dye-doped polymer spheres, [28] organic microdiscs and polymer microspheroids, [29] polymer microrings, [30] dye-doped photonic crystals, [31][32][33][34] organic slab waveguides, [35] polymeric distributed-feedback lasers, [36] micromolded polymer films, [37] and polymer-filled circular gratings.[38] Despite significant activity in organic photonics, the creation of micropatterned organic structures is at a less advanced stage compared to progress made using inorganic semiconductors. This in part results from an increased sensitivity of organic thin films to the techniques commonly used to create high-resolution structures. There are, in fact, very pressing reasons to explore organic materials in new types of photonic structure, as such materials can often display optical properties not readily emulated using inorganic semiconductors. For example, the large oscillator strengths of organic (Frenkel) excitons can result in enhanced light-matter interactions, evidenced by "giant" Rabi splittings at room temperature. [22...

Controlling the interactions between polaritons and molecular vibrations in strongly coupled organic semiconductor microcavities

“…Such increases in cavity Q factor can be readily achieved by creating structures based on two distributed Bragg reflectors, 32 or by creating microcavities based on a micropillar-type geometry. 33 …”

Optical‐Mode Structure of Micropillar Microcavities Containing a Fluorescent Conjugated Polymer

“…Here, Adawi et al. first reported the fabrication of a micropillar microcavity containing a fluorescent molecular dye using an ion‐beam etching technique . Using near‐field optical imaging techniques, it was shown that such structures were able to modify spontaneous emission rates.…”

Spontaneous emission in micro- and nano-structures

“…Schwab [115] presented that the altered SE depends on excitation intensity. Adawi [116] and Bennett [117] also found Purcell effect in pillar microcavity. Recently, using a QD weakly coupled to a micropillar cavity, a single photon sources with an indistinguishability of 90% was reported by Ates [118].…”