Aramais R. Zakharian

Tunable watt-level blue-green vertical-external-cavity surface-emitting lasers by intracavity frequency doubling

We report on the development and the demonstration of a tunable, watt-level, blue-green, linearly polarized vertical-external-cavity surface-emitting lasers operating around 488nm by intracavity second-harmonic generation. By using lithium triborate crystal, we have achieved over 1.3W continuous wave blue-green power at 488nm with a 5nm tunability.

Linearly polarized dual-wavelength vertical-external-cavity surface-emitting laser

Abstract : The authors demonstrate the multiwatt linearly polarized dual-wavelength operation in an optically pumped vertical-external-cavity surface-emitting laser by means of an intracavity tilted Fabry-Perot etalon and a Brewster window. The sum frequency generation from the lithium triborate crystal pumped by this laser confirms that these two wavelengths oscillate simultaneously. Over 30 dB side-mode suppression can be achieved at dual wavelengths with a spectral spacing of 2.1 nm. The output power is slightly reduced by the intracavity Fabry-Perot etalon and Brewster window.

Multichip vertical-external-cavity surface-emitting lasers: a coherent power scaling scheme

We propose an efficient coherent power scaling scheme, the multichip vertical-external-cavity surface-emitting laser (VECSEL), in which the waste heat generated in the active region is distributed on multi-VECSEL chips such that the pump level at the thermal rollover is significantly increased. The advantages of this laser are discussed, and the development and demonstration of a two-chip VECSEL operating around 970 nm with over 19 W of output power is presented.

Extended Tunability in a Two-Chip VECSEL

We demonstrate a widely tunable vertical-external-cavity surface-emitting laser (VECSEL) with a W-shaped cavity, in which two VECSEL chips serve as fold mirrors and a birefringent filter is inserted at Brewsters angle. These two chips provide much higher modal gain and broader bandwidth of the gain than a single chip does, enhancing the VECSEL tuning range and reducing the variation of tunable output power with the tuned wavelength. This two-chip VECSEL configuration makes it possible to shape the modal gain spectra of the laser or to manipulate the tuning curve of the laser by two different chips with certain gain peak detuning (offset). Multiwatts high-brightness linearly polarized output with a tuning range of 33 nm is demonstrated in such a two-chip VECSEL

High-power optically pumped VECSEL using a double-well resonant periodic gain structure

We present the design and fabrication of an optically pumped vertical-external-cavity surface-emitting lasers with double-well resonant periodic gain structure. Each double-well consists of two 4-nm-thick InGaAs strained quantum wells. The double-well provides optimum overlap between the quantum wells and the antinodes of the standing wave of laser signal at high-power and high-temperature operation. The structure is more tolerant to variation of the growth, processing, and operating temperature for maintaining high modal gain. For a 230-/spl mu/m diameter pump spot, over 4-W continuous-wave output with a slope efficiency of 39% is demonstrated at 30/spl deg/C without thermal rollover.

AMR FDTD solver for nanophotonic and plasmonic applications

Uniform, nonuniform and adaptive mesh refinement FDTD approaches to solving 3D Maxwells equations are compared and contrasted. Specific applications of such schemes to optical memory, nanophotonics and plasmonics problems will be illustrated.

Modeling and Experimental Result Analysis for High Power VECSELs

We present a comparison of experimental and microscopically based model results for optically pumped vertical external cavity surface emitting semiconductor lasers. The quantum well gain model is based on a quantitative ab-initio approach that allows calculation of a complex material susceptibility dependence on the wavelength, carrier density and lattice temperature. The gain model is coupled to the macroscopic thermal transport, spatially resolved in both the radial and longitudinal directions, with temperature and carrier density dependent pump absorption. The radial distribution of the refractive index and gain due to temperature variation are computed. Thermal managment issues, highlighted by the experimental data, are discussed. Experimental results indicate a critical dependence of the input power, at which thermal roll-over occurs, on the thermal resistance of the device. This requires minimization of the substrate thickness and optimization of the design and placement of the heatsink. Dependence of the model results on the radiative and non-radiative carrier recombination lifetimes and cavity losses are evaluated.

Simulating near-field effects in high-density optical-disk data storage

Plane-wave expansion methods for classical diffraction theory equations, coupled with the direct numerical solution of Maxwells equations using local grid refinement and the finite-difference time-domain method, help us reliably simulate an optical systems macroscopic and subwavelength components.

Tunable high-power blue-green laser based on intracavity frequency doubling of a diode-pumped vertical-external-cavity surface-emitting laser

We present the development and demonstration of tunable high-power blue-green (around 488 nm) laser by using intracavity frequency doubling of a tunable high-power high-brightness linearly polarization vertical-external-cavity surface-emitting laser.

Application of the finite-difference time-domain (FDTD) method with local grid refinement to nanostructure design

The Finite-Difference Time-Domain (FDTD) method is often a viable alternative to other computational methods used for the design of sub-wavelength components of photonic devices. We describe an FDTD based grid refinement method, which reduces the computational cell size locally, using a collection of nested rectangular grid patches. On each patch, a standard FDTD update of the electromagnetic fields is applied. At the coarse/fine grid interfaces the solution is interpolated, and consistent circulation of the fields is enforced on shared cell edges. Stability and accuracy of the scheme depend critically on the update scheme, space and time interpolation, and a proper implementation of flux conditions at mesh boundaries. Compared to the conformal grid refinement, the method enables better efficiency by using non-conformal grids around the region of interest and by refining both space and time dimensions, which leads to considerable savings in computation time. We discuss the advantages and shortcomings of the method and present its application to the problem of computation of a quality factor of a 3-D photonic crystal microcavity.