Irina Kulkova

Plasmonic modulator based on gain-assisted metal-semiconductor-metal waveguide

We investigate plasmonic modulators with a gain material to be implemented as ultra-compact and ultra-fast active nanodevices in photonic integrated circuits. We analyze metal-semiconductor-metal (MSM) waveguides with InGaAsP-based active material layers as ultra-compact plasmonic modulators. The modulation is achieved by changing the gain of the core that results in different transmittance through the waveguides. A MSM waveguide enables high field localization and therefore high modulation speed. Bulk semiconductor, quantum wells and quantum dots, arranged in either horizontal or vertical layout, are considered as the core of the MSM waveguide. Dependences on the waveguide core size and gain values of various active materials are studied. The designs consider also practical aspects like n- and p-doped layers and barriers in order to obtain results as close to reality. The effective propagation constants in the MSM waveguides are calculated numerically. Their changes in the switching process are considered as a figure of merit. We show that a MSM waveguide with electrical current control of the gain incorporates compactness and deep modulation along with a reasonable level of transmittance.

Metal organic vapor-phase epitaxy of InAs/InGaAsP quantum dots for laser applications at 1.5 μm

The epitaxial growth of InAs/InGaAsP/InP quantum dots (QDs) for emission around 1.5 μm by depositing a thin layer of GaAs on top of the QDs is presented in this letter. The infuence of various growth parameters on the properties of the QDs, in particular, size, shape, chemical composition, and emission wavelength are investigated. Continuous wave lasing in ridge waveguide QD laser structures in the 1.5 μm wavelength range is demonstrated.

Epitaxial growth of quantum dots on InP for device applications operating at the 1.55 μm wavelength range

The development of epitaxial technology for the fabrication of quantum dot (QD) gain material operating in the 1.55 μm wavelength range is a key requirement for the evolvement of telecommunication. High performance QD material demonstrated on GaAs only covers the wavelength region 1-1.35 μm. In order to extract the QD benefits for the longer telecommunication wavelength range the technology of QD fabrication should be developed for InP based materials. In our work, we take advantage of both QD fabrication methods Stranski-Krastanow (SK) and selective area growth (SAG) employing block copolymer lithography. Due to the lower lattice mismatch of InAs/InP compared to InAs/GaAs, InP based QDs have a larger diameter and are shallower compared to GaAs based dots. This shape causes low carrier localization and small energy level separation which leads to a high threshold current, high temperature dependence, and low laser quantum efficiency. Here, we demonstrate that with tailored growth conditions, which suppress surface migration of adatoms during the SK QD formation, much smaller base diameter (13.6nm versus 23nm) and an improved aspect ratio are achieved. In order to gain advantage of non-strain dependent QD formation, we have developed SAG, for which the growth occurs only in the nano-openings of a mask covering the wafer surface. In this case, a wide range of QD composition can be chosen. This method yields high purity material and provides significant freedom for reducing the aspect ratio of QDs with the possibility to approach an ideal QD shape.

Individual optimization of InAlGaAsP-InP sections for 1.55-μm passively mode-locked lasers

We present integrated single QW semiconductor optical amplifier and MQW electroabsorber modulator based on InAlGaAsP-InP materials for application in a monolithic mode-locked laser. Optimized structures with high-quality butt-joint interfaces are demonstrated.

Light modulation abilities of nanostructures

In the work we consider two new routes to impose control on the optical waveguides propagation. The first approach is based on the Kerr effect caused by the THz field, which strength is manifold times enhanced by the presence of a nanoslit in a metallic film surrounding the waveguide. The second approach utilizes the gain-core effect on plasmonics modes in metal-semiconductor-metal structures. Our simulations prove that it is quite reasonable to realize both control schemes experimentally.

Высокая характеристическая температура лазера на квантовых точках InAs/GaAs/InGaAsP с длиной волны излучения около 1.5 мкм, синтезированного на подложке InP

We report on high temperature stability of a near1.5 μm laser synthesized on an InP (001) substrate. Self-organized InAs quantum dots capped with a thin GaAs layer were used as an active region of the laser. An InGaAsP quaternary alloy having the bandgap energy of 1.15 eV was utilized as a waveguiding/matrix layer. A high characteristic temperature of the threshold current of T0 = 205K, evaluated in the temperature range of 20−50◦C, was achieved in ridge waveguide laser diodes. A correlation of T0 values with the bandgap energy of the waveguiding layer was found. Физика и техника полупроводников, 2017, том 51, вып. 10

On the high characteristic temperature of an InAs/GaAs/InGaAsP QD laser with an emission wavelength of ~1.5 μm on an InP substrate

We report on a study of lasers with an emission wavelength of about 1.5 μm and high temperature stability, synthesized on an InP (001) substrate. Self-organized InAs quantum dots capped with a thin GaAs layer are used as the active region of the laser. A quaternary InGaAsP solid solution with a band-gap width of 1.15 eV serves as the waveguide/matrix layer. A high characteristic temperature of the threshold current, T0 = 205 K, is reached in the temperature range 20–50°C in ridge-waveguide laser diodes. A correlation between the values of T0 and the band-gap width of the waveguide layers is found.

Butt-joint integration of active optical components based on InP/AlInGaAsP alloys

We demonstrate all-active planar high quality butt-joint (BJ) integration of a QW Semiconductor Optical Amplifier (SOA) and MQW Electro-Absorption Modulator (EAM) based on an InP/AlInGaAsP platform. The degradation of the optical properties in the vicinity of ~1 μm to the BJ interface was determined by means of μPL measurements.