Spectrally engineered photonic molecules as optical sensors with enhanced sensitivity: a proposal and numerical analysis

Abstract

We report a theoretical study of clusters of evanescently-coupled 2D whispering-gallery (WG) mode optical micro-cavities (termed "photonic molecules") as chemosensing and biosensing platforms. Photonic molecules (PMs) supporting modes with narrow linewidths, wide mode spacing, and greatly enhanced sensitivity to the changes in the dielectric constant of their environment and to the presence of individual sub-wavelengthsized nanoparticles in the PM evanescent-field region are numerically designed. This type of optical biosensor can be fabricated in a variety of material platforms and integrated on a single chip that makes it a promising candidate for a small and robust lab-on-a-chip device. Possible applications of the developed methodology and the designed PM structures to the near-field microscopy, single nano-emitter microcavity lasing, and cavity-controlled single-molecule fluorescence enhancement are also discussed.

Chains of coupled square dielectric optical microcavities

“…2-or 3-D configurations require numerical approximations, where solvers for the field shapes and complex eigenfrequencies of open dielectric cavities are less frequently found. Among the few examples are the FEM modules in the commercial package (JCMwave GmbH), and academic programs of more numerical (Sopaheluwakan 2006) (FEM) or analytical character Prkna 2004;Boriskina 2006) (circular cavities). Probably also the near field solutions at resonances (scattered field part) generated by a computational treatment of specific scattering problems (Boriskina et al 2004Pishko et al 2007), for individual, suitably shaped cavities could be used for this purpose.…”

“…A variety of concepts exist; among these are series of microring or -disk resonators (Yariv et al 1999;Little et al 2004;Morichetti et al 2007), sequences of defects in photonic crystals or photonic crystal slabs (Bayindir et al 2000;Reynolds et al 2001;Scheuer et al 2005), and coupled dielectric spheres (Astratov et al 2004;Chen et al 2006). Some configurations can also be viewed as specific extended cases of photonic molecules (Boriskina 2005(Boriskina , 2006Boriskina et al 2007). …”

Polymeric photonic molecule super-mode lasers on silicon

“…Optically coupled microcavities are attractive devices for the investigation of fundamental physics, e.g., quantum optics, 1-4 as well as for applications, such as sensing [5][6][7][8][9] or telecommunications. 10,11 Two or more coupled microresonators are often referred to as photonic molecule (PM), due to the formation of optical bonding and antibonding modes in analogy to the electronic states in molecules formed by atoms.…”

“…Numerical simulations of PMs predict improved properties for label-free biosensing such as an increased sensitivity compared to single microcavities 5 and the possibility to discriminate-in a self-referenced way-between specific and unspecific binding events, 15 which could make PMs applicable to complex multi-target environments, where unspecific binding events add additional noise to the detection of a specific target.…”

Resonance Splitting in Two Coupled Circular Closed-Loop Arrays and Investigation of Analogy to Traveling-Wave Optical Resonators

“…In TW optical resonators, the case has already been studied [18] as the fundamental representative of a currently attractive class of super-resonators termed "photonic molecules", which includes cluster architectures of coupled resonators [19]. The filter application of the double-microring system has also been proposed for the implementation of tunable optical reflectors [20,21].…”