S. A. Gurevich

Monolithically-integrated hybrid heterostructure diode laser with dielectric-film waveguide DBR

In the monolithically-integrated hybrid (MIH) DBR diode laser, the five-layer Ga(Al)As-GaAs heterostructure waveguide of the gain region was monolithically butt-joined on a common GaAs substrate with a highly-transparent corrugated dielectric-film waveguide consisting of sputtered SiO 2 , Ta 2 O 5 , and evaporated (corrugated) As 2 S 3 layers. The laser operated with the first-order grating under the pulsed current pumping at 300 K. The efficient resonant mode conversion (70 percent in power) has been obtained at the interface between the heterostructure and dielectric waveguides. The fundamental transverse and single-longitudinal mode output emission was obtained up to 160 mW ( Ith = 120 mA) with external differential quantum efficiency \eta \simeq 32 percent. The advantages of a dielectric-film waveguide DBR are demonstrated. The use of such a DBR results in a high degree of sidemode suppression and stability of the spectral position of the emission line under the temperature variation, the corresponding spectral shift being \lsim 0.01 A/K.

Fabrication of semiconductor-and polymer-based photonic crystals using nanoimprint lithography

The technology of fabricating photonic crystals with the use of nanoimprint lithography is described. One-and two-dimensional photonic crystals are produced by direct extrusion of polymethyl methacrylate by Si moulds obtained via interference lithography and reactive ion etching. The period of 2D photonic crystals, which present a square array of holes, ranges from 270 to 700 nm; the aperture diameter amounts to the half-period of the structure. The holes are round-shaped with even edges. One-dimensional GaAs-based photonic crystals are fabricated by reactive ion etching of GaAs to a depth of 1 μm through a mask formed using nanoimprint lithography. The resulting crystals have a period of 800 nm, a ridge width of 200 nm, and smooth nearly vertical side walls.

Edge-emitting InGaAs/GaAs lasers with deeply etched semiconductor/air distributed Bragg reflector mirrors

The fabrication and properties of 18 µm wide, 200 µm long edge-emitting InGaAs/GaAs lasers with a distributed Bragg reflector (DBR) mirror at one cavity end and a cleaved facet at the other are presented. The three-period third-order DBRs with high aspect ratio (~14:1) and nearly vertical sidewalls have been fabricated by reactive ion etching. The device threshold current and maximum output power are 30 mA and 80 mW, respectively. The spectral width of the lasing line is only 2 nm. The reflectivity of the DBR, determined by comparing the differential efficiencies from the DBR and the cleaved facet, is 73%. The width of the far-field pattern from the DBR end in the parallel direction (12°) is slightly larger than that from the cleaved facet (8°). By contrast, the width of the far-field pattern from the DBR end in the perpendicular direction is only 8°, which is five times smaller than that from the cleaved facet.

Impact of Carrier Lateral Transport and Surface Recombination on the PL Efficiency of Mesas with Self‐Organized Quantum Dots

Temperature-dependent photoluminescence study was made of mesa arrays with InAs-GaAs quantum dots. The smallest 0.2 μm mesas demonstrate bright photoluminescence at 300 K indicating that using quantum dots as active medium permits dramatic reduction of surface recombination.

Process of fabricating semiconductor microcavities and photon crystals

A process of fabricating microcavities and photon crystals in GaAs structures by means of electron lithography and reactive ion etching is described. Two types of structures, with micropillars and with photon crystals, are considered. The latter structures have the form of a square or hexagonal array of holes in a planar waveguiding structure. The minimal diameter of the micropillars is 100 nm, and their height is 700 nm. The size of the holes in the photon crystals and the photon crystal period are controllably varied from 140 to 500 nm and from 400 to 1000 nm, respectively. The etch depth of the crystals is more than 350 nm.

Single-Frequency Diode Laser with a High Temperature Stability of the Emission Line

Distributed Bragg reflector (DBR) injection lasers are considered as a promising light source for fiber optical communication systems and integrated optics. Here we report on the fabrication and investigation of a monolithic-hybrid DBR laser — heterostructure laser with DBR on sputtered dielectric waveguide.