Search results

1

Simulation of Modes in Terahertz Quantum-Cascade Microring and Microdisk Lasers

100%

Tamošiūnas V., Kancleris Z., Tamošiūnienė M.

Acta Physica Polonica A

|

2008

|

vol. 113

|

issue 3

917-920

EN

In our contribution, we report on finite-difference time-domain simulations of modes in microring and microdisk terahertz quantum-cascade lasers with external radii of 100 μm and less. Our simulations have revealed a possibility of low radiative loss for lowest and second order whispering gallery modes in such devices, even when the effective mode volume is reduced below the cubic wavelength.

2

Experimental Investigation of Resistive Sensor for High Power Millimetre Wave Pulse Measurement

100%

Simniškis R., Dagys M., Kancleris Ž., Tamošiūnas V.

|

EN

An experimental investigation of a high power millimetre wave pulse sensor is presented. Two groups of sensors with a flat frequency response were fabricated according to results of the optimisation. The frequency response and voltage standing wave ratio were measured and compared with results of the electrodynamical simulations. The largest measured sensitivity variation of the best sensors within waveguide frequency range was±8%. The reasonable agreement between measured and simulated values of the sensitivity was obtained.

3

Resistive Sensor for Short High-Power Microwave Pulse Measurement in Millimeter Wave Range

88%

Tamošiūnas V., Kancleris Ž., Dagys M., Simniškis R., Agee F.

Acta Physica Polonica A

|

2005

|

vol. 107

|

issue 2

420-424

EN

We report on the numerical investigation of the resistive sensor for the 78-118 GHz range. A three-dimensional finite-difference time-domain method was applied to simulate the wave propagation within a waveguide segment with the semiconductor sensor attached to a wider wall of the wave-guide. The electric field distribution, voltage standing-wave ratio and the average electric field dependences on frequency have been determined for several sets of dimensions and specific resistances of the sample. It is demonstrated that a proper selection of the dimensions and specific resistance of the sample can compensate the waveguide dispersion and the decrease of the electron heating effect with frequency. Therefore, a nearly constant sensitivity of the sensor can be obtained for the entire frequency range.

4

Experimental Investigation of High Pulse Power Microwave Resistive Sensor with Flat Frequency Response

88%

Kancleris Ž., Simniškis R., Dagys M., Tamošiūnas V., Ragulis P.

|

EN

Two types of resistive sensors with flat frequency response for microwave pulse power measurements in X-band rectangular waveguide WR-90 up to 100 kW were developed and experimentally investigated. The first type of the sensors demonstrates higher sensitivity and larger output signal, while the second one exhibits better linearity of the output signal. The experimental investigations revealed the sensitivity variation within ± 10% in 8.2-12.2 GHz frequency band.

5

Study of Terahertz Emission from Surfaces of Cu(InGa)Se_2 Layers

64%

Koroliov A., Arlauskas A., Balakauskas S., Šoliūnas M., Maneikis A., Krotkus A., Šetkus A., Tamošiūnas V.

Acta Physica Polonica A

|

2013

|

vol. 124

|

issue 5

846-848

EN

In this contribution, we report on investigations of THz emission from Cu(In,Ga)Se_2 layers, deposited from a single copper-deficient sputtering target. Emission from Cu(In,Ga)Se_2 layer surface and from multilayer structure with transparent ZnO layers were studied. It was determined that additional undoped ZnO layer reduces the amplitude of THz emission, while additional n-type ZnO layers increase the emission amplitude again. This effect can be attributed to stronger electric field in the heterostructure between p-type Cu(In,Ga)Se_2 and n-type ZnO layers.

6

Finite-Difference Time-Domain Simulation of Mid- and Far-Infrared Quantum Cascade Lasers

64%

Tamošiūnas V., Kancleris Ž., Dagys M., Simniškis R., Tamošsiūnienė M., Valušis G., Strasser G., Unterrainer K.

Acta Physica Polonica A

|

2005

|

vol. 107

|

issue 1

179-183

EN

We present simulations of mid- and far-infrared quantum cascade lasers operating with/without external magnetic field. Maxwell-Bloch solver based on the finite-difference time-domain method was used in our investigation. Reduction of the far-infrared quantum cascade laser emission intensity is associated with increased optical losses in highly doped layers when magnetic field is changed from 4.2 T to 6.2 T. A simulated emission spectrum of mid-infrared disc-shaped quantum cascade laser with 60μm radius is consistent with the experimentally observed irregular spacing between quantum cascade laser emission lines.

7

Energy Spectrum of InAs Quantum Dots in GaAs/AlAs Superlattices

64%

Nedzinskas R., Čechavičius B., Kavaliauskas J., Karpus V., Krivaitė G., Tamošiūnas V., Valušis G., Schrey F., Unterrainer K., Strasser G.

Acta Physica Polonica A

|

2008

|

vol. 113

|

issue 3

975-978

EN

Photo- and contactless electroreflectance spectroscopies were applied to study optical properties and electronic structure of GaAs/AlAs superlattice systems with embedded InAs quantum dots. The observed interband transitions related to the quantum dot ground and excited states, as well as optical transitions in the combined system formed by the InAs wetting layer and GaAs/AlAs superlattice are discussed.

8

Broad Band THz Sensing by 2DEG Bow-Tie-Type Diodes

52%

Valušis G., Seliuta D., Tamošiūnas V., Širmulis E., Balakauskas S., Gradauskas J., Sužiedėlis A., Ašmontas S., Anbinderis T., Narkūnas A., Papsujeva I., Lisauskas A., Roskos H., Köhler K.

Acta Physica Polonica A

|

2005

|

vol. 107

|

issue 1

184-187

EN

We suggest a novel approach to detect broad band, 0.078-2.52 THz, electromagnetic radiation at room temperature using an asymmetrically-shaped bow-tie diode based on a modulation-doped GaAs/AlGaAs structure. We show that the voltage sensitivity in the range from 0.078 THz up to 0.8 THz has a plateau and its value is within 0.3-0.5 V/W. We consider the bow-tie diode design to increase the sensitivity of the device.

Refine search results

Simulation of Modes in Terahertz Quantum-Cascade Microring and Microdisk Lasers

Experimental Investigation of Resistive Sensor for High Power Millimetre Wave Pulse Measurement

Resistive Sensor for Short High-Power Microwave Pulse Measurement in Millimeter Wave Range

Experimental Investigation of High Pulse Power Microwave Resistive Sensor with Flat Frequency Response

Study of Terahertz Emission from Surfaces of Cu(InGa)Se_2 Layers

Finite-Difference Time-Domain Simulation of Mid- and Far-Infrared Quantum Cascade Lasers

Energy Spectrum of InAs Quantum Dots in GaAs/AlAs Superlattices

Broad Band THz Sensing by 2DEG Bow-Tie-Type Diodes