Meir Orenstein

Transverse mode characteristics of vertical cavity surface-emitting lasers

Transverse mode characteristics of vertical cavity surface‐emitting (VC‐SE) lasers are described. The mode structure is investigated as a function of the transverse dimension for proton‐implanted gain‐guided VC‐SE lasers. A comparison is made to an air‐post index‐guided structure. The lasing modes and the evolution of the modes with increasing drive current for the VC‐SE lasers are observed to be highly analogous to those of the edge‐emitting lasers. Broad‐area gain‐guided lasers lase in the fundamental TEM00 mode near threshold. At higher currents, high‐order modes are successively excited. A 5 μm square proton‐implanted gain‐guided VC‐SE laser emits a single mode. On the other hand, an air‐post index‐guided SE laser, due to the large index difference between the laser and the cladding, emits multiple transverse modes. Moreover, we show that the gain‐guided VC‐SE lasers exhibit better device characteristics than the air‐post index‐guided lasers.

Two‐dimensional phase‐locked arrays of vertical‐cavity semiconductor lasers by mirror reflectivity modulation

Coupling of two‐dimensional (2D) vertical‐cavity surface‐emitting lasers (VCSELs) to give a coherent supermode is described. The top metal layer of a stained‐layer InGaAs quantum well VCSEL structure was patterned laterally by depositing various metals with different optical reflectivities. This lateral reflectivity patterning defined a 2D laser array sharing the same ‘‘supercavity’’. It is shown that these 2D arrays oscillate in a stable single, coherent 2D supermode. This was achieved with a simple planar process and without significant deterioration of threshold current and efficiency relative to an equivalent broad‐area VCSEL.

Gap plasmon polariton structure for very efficient microscale-to-nanoscale interfacing.

The seamless transition between microscale photonics and nanoscale plasmonics requires overpassing different waveguiding mechanisms and a few orders of magnitude in the lateral dimension. Exploiting gap plasmon-polariton waves both at the microscale and nanoscale with an ultrashort (few micrometers) nonadiabatic tapered gap plasmon waveguide, we show theoretically that very high-power transfer efficiency (approximately 70%) is achieved. The same mechanism may be used to harvest impinging light waves and direct them into a nanohole or slit to exhibit an anomalous transmission without the conventional periodic structures. The interplay of plasmonic and oscillating modes is analyzed.

Large two‐dimensional arrays of phase‐locked vertical cavity surface emitting lasers

The phase‐locking of two‐dimensional (2D) arrays incorporating a large number of electrically pumped, vertical cavity surface emitting lasers (VCSELs) is described. The InGaAs/GaAs quantum well VCSELs are phase locked by patterning the reflectivity of the laser back mirrors. Structures with both weak and strong modulation of the mirror reflectivity have been studied. The strongly modulated (weakly coupled) structures exhibit superior coherence and beam patterns, with up to 27×27 lasers oscillating in virtually a single (highest order) supermode. The weakly modulated (strongly coupled) arrays also emit highly coherent beams, but with lower threshold currents and higher differential efficiencies. Weakly modulated arrays of 20×20 elements (120×120 μm2) exhibited threshold currents of <1 mA per laser and ≳300 mW pulsed output powers. These coherent 2D arrays should be useful for optical signal processing and high optical power applications.

Multimode add-drop multiplexing by adiabatic linearly tapered coupling.

Multimode multiplexing can potentially replace WDM for implementing multichannel short reach interconnects. Multiple optical modes can thus be exploited as the channels for transferring optical data, where each mode represents an independent data channel. The basic building block of the system is a Mode Add/Drop which can be implemented based on adiabatic power transfer. We propose a new scheme for realization of such adiabatic mode add drop with a predefined coupling profile, and demonstrate it by employing a linearly decreasing coupling coefficient along the propagation length. Realization using Silicon-On- Insulator (SOI) platform is discussed - which offers the possibility of direct integration of the optoelectronic circuitry with the Si processor.

Electrical characteristics of metal-dielectric-metal and metal-dielectric-semiconductor structures based on electron beam evaporated Y2O3, Ta2O5 and Al2O3 thin film

This work examines the electrical properties of metal-dielectric-semiconductor (Au/Ti–D–pSi) and metal-dielectric-metal (Au/Ti–D–Pt/Ti–pSi) capacitors which incorporate as dielectrics Y2O3, Al2O3 and Ta2O5 films evaporated by an electron beam at room temperature. The emphasis of the results is twofold: the first is the high quality of the investigated films as evidenced by the small measured values of loss factor, flatband voltages, and surface states density as well as the low dispersion of the relative dielectric constants. The second is an analytical procedure for discrimination of current flow mechanisms, under different regimes of applied voltage. A detailed study of the power exponent parameter α=d(Log I)/d(Log V) was found to be superior to conventional graphical representation of I–V data. The dominant mechanisms of charge transport through the metal-dielectric-metal structures was found to be the Schottky emission for Y2O3 and Al2O3 at low electrical fields. For structures with Y2O3 and Ta2O5 fil...

Modeling of Complementary (Void) Plasmon Waveguiding

Plasmonic circuit elements, which are based on complementary waveguide structures (waveguides with a dielectric core and metal cladding), are becoming preferred plasmonic devices for applications. In this paper, we look into the modeling of such devices, namely 1D waveguides and related elements as well as 2D slots, trenches, and channels supporting plasmonic slow waves. Methods such as the effective index, finite-difference time domain, finite elements, or other full-vectorial propagation schemes are among the methods discussed, and their limitations in the field of plasmonics are set. We believe that although many successful validated modeling methods were presented intensive efforts are still required for perfecting the various tools to faithfully describe nanosized plasmonic wave propagation on high-contrast nanometal discontinuities.

Nano-plasmonic antennas in the near infrared regime

Plasmonic nano-antennas constitute a central research topic in current science and engineering with an enormous variety of potential applications. Here we review the recent progress in the niche of plasmonic nano-antennas operating in the near infrared part of the spectrum which is important for a variety of applications. Tuning of the resonance into the near infrared regime is emphasized in the perspectives of fabrication, measurement, modeling, and analytical treatments, concentrating on the vast recent achievements in these areas.

Vertical-cavity surface-emitting InGaAs/GaAs lasers with planar lateral definition

A planarity preserving method for the definition of vertical‐cavity surface‐emitting lasers (VC‐SEL) is described. A strained‐layer InGaAs quantum well VC‐SEL structure was grown and lasers were laterally defined using a tailored deep proton implantation process. In these lasers we obtained low threshold current densities of 1000 A/cm2 and efficient cw operation. This method facilitates large‐scale integration of VC‐SEL devices.

Nonlocal ponderomotive nonlinearity in plasmonics

We analyze an inherent nonlinearity of surface plasmon polaritons at the interface of Fermi-Dirac metal plasma, stemming from the depletion of electron density in high-intensity regions. The derived optical nonlinear coefficients are comparable with the experimental values for metals. We calculate the dispersion relations for the nonlinear propagation of high-intensity surface plasmon polaritons, predicting a nonlinearity-induced cutoff and vanishing group velocity.