Methods for controlling positions of guided modes of photonic-crystal waveguides

We analyze different methods for controlling positions of guided modes of planar photonic-crystal waveguides. Methods based both on rearrangements of holes in the photonic-crystal lattice and on changes of hole sizes are presented. The ability to tune frequencies of guided modes within a frequency bandgap is necessary to achieve efficient guiding of light within a waveguide, as well as to match frequencies of eigenmodes of different photonic-crystal-based devices for the purpose of good coupling between them. We observe and explain the appearance of acceptor-type modes in donor-type waveguides

Optimal pulse to generate non-classical photon states via photon blockade

The single photon character of nonclassical states of light that can be generated using photon blockade is analyzed for time domain operation. We show that improved single photon statistics (single photon around 85% with a multi-photon of 8%) can be obtained by adequately choosing the parameters (mainly amplitude and pulse-duration) of the driving laser pulses. An alternative method, where the system is driven via a continuous wave laser and the frequency of the dipole is controlled (e.g. electrically) at very fast timescales is presented. We also show that this non-classical state performs better than a weak coherent pulse, when applied to BB84 quantum cryptography protocol

Surface plasmon enhanced light-emitting diode

A method for enhancing the emission properties of light-emitting diodes, by coupling to surface plasmons, is analyzed both theoretically and experimentally. The analyzed structure consists of a semiconductor emitter layer thinner than λ/2 sandwiched between two metal films. If a periodic pattern is defined in the top semitransparent metal layer by lithography, it is possible to efficiently couple out the light emitted from the semiconductor and to simultaneously enhance the spontaneous emission rate. For the analyzed designs, we theoretically estimate extraction efficiencies as high as 37% and Purcell factors of up to 4.5. We have experimentally measured photoluminescence intensities of up to 46 times higher in fabricated structures compared to unprocessed wafers. The increased light emission is due to an increase in the efficiency and an increase in the pumping intensity resulting from trapping of pump photons within the microcavity

Engineering anti-bunching via photon blockade in photonic crystal cavity-quantum dot systems

Methods to improve single photon generation via photon-blockade in a photonic-crystal cavity with a strongly coupled quantum-dot are presented. With realistic system parameters, significant improvement in second-order-auto-correlation g^2 (0) (from 0.93 to 0.79) is achieved

Generation of nonclassical states of light via photon blockade in optical nanocavities

The generation of nonclassical states of light via photon blockade with time-modulated input is analyzed. We show that improved single-photon statistics can be obtained by adequately choosing the parameters of the driving laser pulses. An alternative method, where the system is driven via a continuous-wave laser and the frequency of the dipole is controlled (e.g., electrically) at very fast time scales is presented

Finite-difference time-domain calculation of the spontaneous-emission coupling factor in optical microcavities

We present a general method for the β factor calculation in optical microcavities. The analysis is based on the classical model for atomic transitions in a semiconductor active medium. The finite-difference time-domain method is used to evolve the electromagnetic fields of the system and calculate the total radiated energy, as well as the energy radiated into the mode of interest. We analyze the microdisk laser and compare our result with the previous theoretical and experimental analyses. We also calculate the β factor of the microcavity based on a two-dimensional (2-D) photonic crystal in an optically thin dielectric slab. From the β calculations, we are able to estimate the coupling to radiation modes in both the microdisk and the 2-D photonic crystal cavity, thereby showing the effectiveness of the photonic crystal in suppressing in-plane radiation modes

Coherent probing and saturation of a strongly coupled quantum dot

We coherently probe a quantum dot, strongly coupled to a photonic crystal nano-cavity, using a resonant laser beam. At higher pump power, the coupled systempsilas response becomes highly nonlinear. This coherent probing method has applications for classical and quantum information processing

Single photon nonlinear optics in photonic crystals

We coherently probe a quantum dot that is strongly coupled to a photonic crystal nano-cavity by scattering of a resonant laser beam. The coupled system's response is highly nonlinear as the quantum dot saturates with nearly one photon per cavity lifetime. This system enables large amplitude and phase shifts of a signal beam via a control beam, both at single photon levels. We demonstrate photon-photon interactions with short pulses in a system that is promising for ultra-low power switches and two-qubit quantum gates

Theoretical and Experimental Investigation of Efficient Photonic Crystal Cavity-Waveguide Couplers

Coupling of photonic crystal (PC) linear three-hole defect cavities to PC waveguides is theoretically and experimentally investigated. An improved coupling is obtained by tilting the cavity axis by 60° with respect to the waveguide direction

Design and Fabrication of Silicon Photonic Crystal Optical Waveguides

We have designed and fabricated waveguides that incorporate two-dimensional (2-D) photonic crystal geometry for lateral confinement of light, and total internal reflection for vertical confinement. Both square and triangular photonic crystal lattices were analyzed. A three-dimensional (3-D) finite-difference time-domain (FDTD) analysis was used to find design parameters of the photonic crystal and to calculate dispersion relations for the guided modes in the waveguide structure. We have developed a new fabrication technique to define these waveguides into silicon-on-insulator material. The waveguides are suspended in air in order to improve confinement in the vertical direction and symmetry properties of the structure. High-resolution fabrication allowed us to include different types of bends and optical cavities within the waveguides