2D Photonic Crystal Microcavities Research Articles

Quantum many-body simulation using monolayer exciton-polaritons in coupled-cavities

Quantum simulation is a promising approach to understanding complex strongly correlated many-body systems using relatively simple and tractable systems. Photon-based quantum simulators have great advantages due to the possibility of direct measurements of multi-particle correlations and ease of simulating non-equilibrium physics. However, interparticle interaction in existing photonic systems is often too weak, limiting the potential for quantum simulation. Here we propose an approach to enhance the interparticle interaction using exciton-polaritons in MoS2 monolayer quantum dots embedded in 2D photonic crystal microcavities. Realistic calculation yields optimal repulsive interaction in the range of 1–10 meV—more than an order of magnitude greater than the state-of-the-art value. Such strong repulsive interaction is found to emerge neither in the photon-blockade regime for small quantum dot nor in the polariton-blockade regime for large quantum dot, but in the crossover between the two regimes with a moderate quantum-dot radius around 20 nm. The optimal repulsive interaction is found to be largest in MoS2 among commonly used optoelectronic materials. Quantum simulation of strongly correlated many-body systems in a finite chain of coupled cavities and its experimental signature are studied via the exact diagonalization of the many-body Hamiltonian. A method to simulate 1D superlattices for interacting exciton-polariton gases in serially coupled cavities is also proposed. Realistic considerations on experimental realizations reveal advantages of transition metal dichalcogenide monolayer quantum dots over conventional semiconductor quantum emitters.

Review of design principles of 2D photonic crystal microcavity biosensors in silicon and their applications

In this paper, we reviewed the design principles of two-dimensional (2D) silicon photonic crystal microcavity (PCM) biosensors coupled to photonic crystal waveguides (PCWs). Microcavity radiation loss is controlled by engineered the cavity mode volume. Coupling loss into the waveguide is controlled by adjusting the position of the microcavity from the waveguide. We also investigated the dependence of analyte overlap integral (also called fill fraction) of the resonant mode as well as the effect of group index of the coupling waveguide at the resonant wavelength of the microcavity. In addition to the cavity properties, absorbance of the sensing medium or analyte together with the affinity constant of the probe and target biomarkers involved in the biochemical reaction also limits the minimum detection limits. We summarized our results in applications in cancer biomarker detection, heavy metal sensing and therapeutic drug monitoring.

A New Structure of the 2D Photonic Crystal Microcavities with Hexagonal Lattice

A new 2D photonic crystal microcavity is proposed based on the localized modulation and the model match technique. Structure of the new PC cavity is characterized in that several scatters are introduced into the edges of the L3 microcavities. The local field modulation method is applied in the new PC microcavity to optimize the cavity structure, and the quality factor Q and transmission T can be both improved after modulation. During the modulation process, Q and T of the new PC cavity represent an identical variation trend. The Q and T of the optimized PC cavity, with the simulation parameters confined in our work, reach to 240000 and 0.68 respectively.

High-Q hybrid 3D-2D slab-3D photonic crystal microcavity

The radiation loss in the escaping light cone with a two-dimensional (2D) photonic crystal slab microcavity can be suppressed by means of cladding the low-Q slab microcavity by three-dimensional woodpile photonic crystals with the complete bandgap when the resonance frequency is located inside the complete bandgap. It is confirmed that the hybrid microcavity based on a low-Q, single-defect photonic crystal slab microcavity shows improvement of the Q factor without affecting the mode volume and modal frequency. Whereas 2D slab microcavities exhibit Q saturation with an increase in the number of layers, for the analyzed hybrid microcavities with a small gap between the slab and woodpiles, the Q factor does not saturate.

The investigation of variation of transmission T during the improvement of Q of the 2D photonic crystal microcavities by local field modulation

The effects of modulations applied to the side air rods of two-dimensional (2D) photonic crystal (PC) microcavities on the quality factor Q and the transmission T have been numerically investigated using the multiple-scattering approach for transverse magnetic modes. The investigated 2D PC microcavity with hexagonal lattice is composed of an array of n × n air rods in Si substrates with three air rods removed from the centre, where n is the number of air rods located at the X- and Y-axes. The modulations are attempted by decreasing the size, displacing the position and both decreasing the size and shifting the positions of the side air rods, respectively. From the work, the simulation results show that the Q can be increased by the modulation by changing the field distribution, while T changes vastly. For all microcavities investigated in this work, as a result of the modulations, both Q and T are strongly correlated with the modulations and T will always decrease with the increase in Q.

Influence of Dielectric Loss on Quality Factors of Photonic Crystal Microcavity Modes

We numerically investigate the quality factors of two-dimensional (2D) photonic crystal (PC) microcavities using an auxiliary differential equations (ADE) technique in the context of finite-difference time-domain (FDTD) method. The microcavities are formed by point defects in the air hole lattice hexagonally patterned in ZnO (zinc oxide) matrix. The quality factors of these microcavities are limited primarily by the absorption of the background dielectric. We show that the ratio between the quality factors of microcavities in lossy and lossless background dielectric depends on the overlap between the field of cavity modes and the absorbing background dielectric in addition to the magnitude of absorption. These results will be helpful when designing and optimizing photonic crystal microcavities formed in lossy medium.

光子晶体微腔生化传感器的研究

The ultra-compact biosensor based on the two-dimensional (2D) photonic crystal (PhC) microcavity is investigated. The performances of the sensor are analyzed theoretically using the Fabry-Perot (F-P) cavity model and simulated using the finite-difference time-domain (FDTD) method. The simulation results go along with the theoretical analysis.

Near-field mapping of quantum dot emission from single-photonic crystal cavity modes

We directly investigate, by means of near-field spectroscopy, the spatial distribution of the optical cavity modes of 2D photonic crystal microcavities. Numerical simulations confirm that the photoluminescence maps of quantum dots embedded in the photonic structure qualitatively match the spatial modulation of the electric field intensity.

Influence of random errors on the characteristics of typical 2D photonic crystal microcavity

We studied theoretically how random errors which may arise during fabrication, including radius and position Errors, can affect the most fundamental properties of typical 2D photonic crystal microcavities (single defect modes in a 2D square lattice). It is shown that the disorder caused by radius and position errors has little influence on the quality factor but has a large influence on the resonance frequency, given the gain width of conventional semiconductors. In addition, the resonant mode distribution is tolerant to large radius errors but sensitive to position errors.

Enhancement of the SHG efficiency in a doubly resonant 2D-photonic crystal microcavity

In this paper we discuss the conditions to obtain the enhancement of second harmonic generation in a two-dimensional circular photonic crystal AlGaAs cavity. The photonic crystal circular cavity offers the possibility of having high-Q resonance modes with respect to those obtained with other types of photonic crystal lattices. The crystallographic cut of the AlGaAs provides a strong nonlinear coupling between a transverse-magnetic (TM) polarized resonant mode at the fundamental wavelength and a transverse-electric (TE) polarized resonant mode at second harmonic wavelength. The double resonance condition leads to a strong improvement of the second harmonic generation process. A preliminary linear analysis has been performed by using the finite-difference time-domain method, which includes the dispersive response of the material, modeled using the well-known one-pole pair Lorentzian function.

Investigation of cavity modes and direct observation of Purcell enhancement in 2D photonic crystal defect microcavities

We demonstrate our ability to control and manipulate the optical modes in 2D Photonic Crystal Defect cavities and investigate their coupling to InGaAs self-assembled quantum dots. Our results enable us to probe the nature of individual cavity modes and directly investigate cavity QED phenomena. For the lowest mode volume cavities investigated, consisting of a single missing air hole within a hexagonal lattice, we have measured a clear Purcell enhancement of the light-matter interaction in the weak coupling regime. For QDs on-resonance with localized cavity modes this translates to a shortening of the quantum dot spontaneous emission lifetime by a factor ∼2 when compared to off-resonance dots.

InP 2D photonic crystal microlasers on silicon wafer: room temperature operation at 1.55 [micro sign

Room temperature pulsed laser operation of 2D photonic crystal microcavities around 1.55 /spl mu/m is reported. Such devices are based on thin III/V heterostructures transferred onto silicon and include an InGaAs/InP multiquantum well (MQW) active layer.