Alexei A. Erchak

Enhanced coupling to vertical radiation using a two-dimensional photonic crystal in a semiconductor light-emitting diode

Enhanced coupling to vertical radiation is obtained from a light-emitting diode using a two-dimensional photonic crystal that lies entirely inside the upper cladding layer of an asymmetric quantum well structure. A sixfold enhancement in light extraction in the vertical direction is obtained without the photonic crystal penetrating the active material. The photonic crystal is also used to couple pump light at normal incidence into the structure, providing strong optical excitation.

Oxidized GaAs/AlAs mirror with a quantum-well saturable absorber for ultrashort-pulse Cr4+:YAG laser

Abstract Ultra-broadband saturable Bragg reflectors consisting of a 7-period GaAs/Al x O y Bragg mirror and an InGaAs/InP quantum well were studied and used to start modelocking of 36 fs pulses near 1500 nm in a dispersion compensated Cr 4+ :YAG laser. The mirrors are comprised of high-index-contrast GaAs/Al x O y Bragg stacks grown as GaAs/AlAs and oxidized to create mirror areas as wide as 300 μm. They exhibit non-saturable losses smaller than 0.8% and a stopband from 1300 to 1800 nm, indicating the potential for the generation of shorter pulses.

Design of a nanoelectromechanical high-index-contrast guided-wave optical switch for single-mode operation at 1.55 μm

A design is presented for a nanoelectromechanical optical switch based on the horizontal deflection of an input waveguide to align with one of two output waveguides. The use of high-index (GaAs) strip waveguides surrounded by air, designed to be single-mode at 1.55 /spl mu/m, significantly decreases device dimensions as compared to previous designs. Design tradeoffs between optical and mechanical properties of the device are discussed. By means of three-dimensional numerical simulations, optical transmission is optimized for two different design strategies: butt and parallel coupling. High polarization-independent transmission (over 90%) is predicted for realistic design parameters.

Large scale oxidation of AlAs layers for broadband saturable Bragg reflectors

Summary form only given. Describes oxidation of AlAs to Al/sub x/O/sub y/ for use as a broadband saturable Bragg reflector (SBR) where an Al/sub x/O/sub y//GaAs mirror with lateral dimensions >300 /spl mu/m is required. For the SBR structure described, the simulated bandwidth extends from 1200 nm to 1800 nm with greater than 99.5% reflectivity. The layers within the SBR are grown using gas-source molecular beam epitaxy. The SBR structure contains an 8 period GaAs/AlAs quarter-wave stack grown on a GaAs substrate. The Al/sub x/O/sub y/ layer is initially grown as AlAs and later oxidized. The AlAs layer is relatively thick (240 nm) to correspond to a quarter wavelength in Al/sub x/O/sub y/ (n = 1.66) minus a 10% shrinkage upon oxidation. The active region consists of an InP/InGaAs quantum well emitting near /spl lambda/ = 1550 nm. The effects of the SBR for self-starting the laser cavity are detailed.

A few-cycle Cr/sup 4+/:YAG laser

Summary form only given. Kerr-lens mode locked Cr/sup 4+/:YAG lasers are used to generate ultrashort optical pulses near 1.5 /spl mu/m because of their large spectral bandwidth. Pulses as short as 43 fs and 44 fs self-started by a saturable absorber mirror have been generated from Cr/sup 4+/:YAG lasers using fused silica prism pairs for group velocity dispersion compensation.

Increased light extraction from a light-emitting diode using a two-dimensional photonic crystal

Summary form only given. Enhanced light extraction is obtained from a light-emitting diode (LED) containing a two-dimensional (2D) photonic band gap (PBG) crystal. The 2D photonic crystal prohibits the propagation of light within a certain range of frequencies in the plane of the PBG. Several methods to modify light emission using a 2D photonic crystal have been studied. A 2D PBG is fabricated in the top cladding layer of an InGaP/InGaAs quantum well structure that emits at /spl lambda/=980 nm. The photonic crystal is designed such that the emission wavelength lies inside the photonic band gap eliminating the coupling to lateral guided modes within the semiconductor, that is a major source of loss in conventional LEDs. In our experiments, the surface normal photoluminescence (PL) at 980 nm is enhanced by a factor of 6 in the presence of a photonic crystal.

Efficient coupling of radiation into guided slab resonances through two-dimensional photonic crystal

Coupling of radiation to /spl Gamma/ point photonic crystal resonances is explored through photoluminescence measurements. Photoluminescence from a quantum well embedded in a two-dimensional photonic crystal is enhanced by resonant fields. Experiments and simulations are compared.Coupling of radiation to /spl Gamma/ point photonic crystal resonances is explored through photoluminescence measurements. Photoluminescence from a quantum well embedded in a two-dimensional photonic crystal is enhanced by resonant fields. Experiments and simulations are compared.