Ultrafast-nonlinear ultraviolet pulse modulation in an AlInGaN polariton waveguide operating up to room temperature

Ultrafast nonlinear photonics enables a host of applications in advanced on-chip spectroscopy and information processing. These rely on a strong intensity dependent (nonlinear) refractive index capable of modulating optical pulses on sub-picosecond timescales and on length scales suitable for integrated photonics. Currently there is no platform that can provide this for the UV spectral range where broadband spectra generated by nonlinear modulation can pave the way to new on-chip ultrafast (bio-) chemical spectroscopy devices. We introduce an AlInGaN waveguide supporting highly nonlinear UV hybrid light-matter states (exciton-polaritons) up to room temperature. We experimentally demonstrate ultrafast nonlinear spectral broadening of UV pulses in a compact 100 micrometer long device and measure a nonlinearity 1000 times that in common UV nonlinear materials and comparable to non-UV polariton devices. Our demonstration, utilising the mature AlInGaN platform, promises to underpin a new generation of integrated UV nonlinear light sources for advanced spectroscopy and measurement

Optical Nonlinearities in PbSe Nanocrystals

The linear and nonlinear optical response of colloidal PbSe nanocrystals was investigated. Optical nonlinearity and its recovery dynamics in this system was measured and compared with other available experimental data. The saturation irradiance value for the bleaching effect and absorption cross-section were determined

Optical Nonlinearities in PbSe Nanocrystals

The linear and nonlinear optical response of colloidal PbSe nanocrystals was investigated. Optical nonlinearity and its recovery dynamics in this system was measured and compared with other available experimental data. The saturation irradiance value for the bleaching effect and absorption cross-section were determined

Puslaidininkės medžiagos ultrasparčiajai optoelektronikai

The paper presents a review of experimental investigations of various semiconductor materials used for the development of ultrafast optoelectronic devices activated by femtosecond laser pulses that have been performed at the Optoelectronics Laboratory of the Semiconductor Physics Institute during the period from 1997 to 2008. Technology and physical characteristics of low-temperature-grown GaAs and GaBiAs layers as well as the effect of terahertz radiation from the femtosecond laser excited semiconductor surfaces are described and analysed.Lietuviška santrauka. Pateikta įvairių puslaidininkinių medžiagų, naudojamų kuriant ultrasparčius optoelektronikos prietaisus, žadinamus femtosekundiniais lazeriais, ekspwerimentinių tyrimų apžvalga. Tyrimai atlikti Puslaidininkių fizikos instituto Optoelektronikos laboratorijoje1997-2008 metais. Aprašyta žemoje temperatūroje augintų GaAs ir GaBiAssluoksnių technologija ir fizikinės savybės. Išsamiai aptyartas ir išanalizuotas THz spinduliuotės generavimas iš femtosekundiniu lazeriu sužadintų puslaidininkių paviršiaus

Terahertz time-domain-spectroscopy system based on 1.55 μm fiber laser and photoconductive antennas from dilute bismides

We describe a terahertz time-domain-spectroscopy system that is based on photoconductive components fabricated from (GaIn)(AsBi) epitaxial layers and activated by femtosecond 1.55 μm pulses emitted by an Er-doped fiber laser. (GaIn)(AsBi) alloy grown on GaAs substrates contained 12.5%In and 8.5%Bi – a composition corresponding to a symmetrical approach of the conduction and valence band edges to each other. The layers were photosensitive to 1.55 μm wavelength radiation, had relatively large resistivities, and subpicosecond carrier lifetimes – a set of material parameters necessary for fabrication of efficient ultrafast photoconductor devices. The frequency limit of this system was 4.5 THz, its signal-to-noise ratio 65 dB. These parameters were comparable to their typical values for much bulkier solid-state laser based systems

Spontaneous atomic ordering of dilute GaAsBi bismides: Structural and optical study

International audienceThe investigated dilute GaAs 1-x Bi x (x = 0.034-0.052) bismides have been MBE-grown on exact and low-angle offcut (001) GaAs as well as on (001) Ge substrates. Atomic-resolution scanning transmission electron microscopy and X-ray diffraction measurements show the presence of spontaneous CuPt B-type ordering in all the bismide samples. The ordering lifts the valence band degeneracy and induces the optical polarization anisotropy, which manifests in photoluminescence and transmittance spectra of the bismides samples, and is also confirmed by birefringence and linear dichroism measurements. The ordering-induced valence band splitting in dilute GaAs 1-x Bi x is estimated to be much larger than that in the conventional III-V semiconductor alloys (e.g. GaInP)