Effect of active region position in Fabry-Perot single transverse mode broad-waveguide InGaAsP/InP lasers

The dependence of laser performance on the active region position in broad-waveguide laser diodes is presented in this paper. Performance of structures with different position of active region is compared in simulation and actual devices. Lasers with active region displaced towards the p-cladding layer outperformed the lasers with active region undisplaced or displaced towards the n-cladding layer both in simulation and experimentally. Maximum output power increased by 25% for devices with active region displaced towards the p-cladding layer.The Australian Research Council is acknowledged for its financial support

Merged beam laser design for reduction of gain-saturation and two-photon absorption in high power single mode semiconductor lasers

In this paper we report a method to overcome the limitations of gain-saturation and two-photon absorption faced by developers of high power single mode InP-based lasers and semiconductor optical amplifiers (SOA) including those based on wide-waveguide or slab-coupled optical waveguide laser (SCOWL) technology. The method is based on Y-coupling design of the laser cavity. The reduction in gain-saturation and two-photon absorption in the merged beam laser structures (MBL) are obtained by reducing the intensity of electromagnetic field in the laser cavity. Standard ridge-waveguide lasers and MBLs were fabricated, tested and compared. Despite a slightly higher threshold current, the reduced gain-saturation in MBLs results in higher output power. The MBLs also produced a single spatial mode, as well as a strongly dominating single spectral mode which is the inherent feature of MBL-type cavity.The Australian Research Council is acknowledged for its financial support

InP-In<inf>x</inf>Ga<inf>1-x</inf>As core-multi-shell nanowire quantum wells with tunable emission in the 1.3-1.55 μm wavelength range

© 2017 The Royal Society of Chemistry. The usability and tunability of the essential InP-InGaAs material combination in nanowire-based quantum wells (QWs) are assessed. The wurtzite phase core-multi-shell InP-InGaAs-InP nanowire QWs are characterised using cross-section transmission electron microscopy and photoluminescence measurements. The InP-InGaAs direct interface is found to be sharp while the InGaAs-InP inverted interface is more diffused, in agreement with their planar counterpart. Bright emission is observed from the single nanowires containing the QWs at room temperature, with no emission from the InP core or outer barrier. The tunability of the QW emission wavelength in the 1.3-1.55 μm communication wavelength range is demonstrated by varying the QW thickness and in the 1.3 μm range by varying the composition. The experiments are supported by simulation of the emission wavelength of the wurtzite phase InP-InGaAs QWs in the thickness range considered. The radial heterostructure is further extended to design multiple QWs with bright emission, therefore establishing the capability of this material system for nanowire based optical devices for communication applications

InP-InxGa1-xAs core-multi-shell nanowire quantum wells with tunable emission in the 1.3-1.55 µm wavelength range

The usability and tunability of the essential InP–InGaAs material combination in nanowire-based quantum wells (QWs) are assessed. The wurtzite phase core-multi-shell InP–InGaAs–InP nanowire QWs are characterised using cross-section transmission electron microscopy and photoluminescence measurements. The InP–InGaAs direct interface is found to be sharp while the InGaAs–InP inverted interface is more diffused, in agreement with their planar counterpart. Bright emission is observed from the single nanowires containing the QWs at room temperature, with no emission from the InP core or outer barrier. The tunability of the QW emission wavelength in the 1.3–1.55 μm communication wavelength range is demonstrated by varying the QW thickness and in the 1.3 μm range by varying the composition. The experiments are supported by simulation of the emission wavelength of the wurtzite phase InP–InGaAs QWs in the thickness range considered. The radial heterostructure is further extended to design multiple QWs with bright emission, therefore establishing the capability of this material system for nanowire based optical devices for communication applications

Supporting information for InP-InxGa1-x as core-multi-shell nanowire quantum wells with tunable emission in the 1.3 – 1.55 μm wavelength range

Section 1: Experimental details pertaining to the growth of InP- InxGa1-xAs QWs InP nanowire core: The InP nanowire cores were seeded by 50 nm colloidal Au particles. The Au particle-deposited InP (111)B substrates were heated to the growth temperature of 450˚C. Substrates were not annealed prior to growth, but TMIn was pre-flown for 15 s before initiating the growth. This pre-flow step reduces the non-vertical nanowire growths that arise from lack of alloying when the pre-growth annealing step is avoided. The TMIn and PH3 flows were 1.62 × 10-5 and 5 × 10-3 mol/min, respectively. Nanowire core growth was carried out for 30 min at 100 mbar reactor pressure. InxGa1-xAs QWs: After the core growth, the temperature was ramped up to the shell growth temperature of 550˚C and the reactor pressure was ramped to 180 mbar which was the pressure normally used in the current MOVPE system for InP-related planar vapour-solid epitaxial growth. The nanowire core was annealed for 3 min before depositing a thin InP buffer layer on the nanowire side facets in order to ensure a high quality surface for the subsequent QW growth. After a growth interruption of 5 s the QW growth was initiated. The TMIn, TMGa and AsH3 flows used for the study of the effect of QW thickness variation were 6.75 × 10-6, 5.51 × 10-6 and 1.34 × 10-3 mol/min, respectively, giving a vapour phase In molar fraction Xv = [TMIn]/([TMIn]+[TMGa]) of 0.55. The QW growth time was varied between 20 to 180 s depending on the targeted QW thickness. For the study of QW composition variation, the TMIn flow was kept constant at 6.75 × 10-6 mol/min while varying the TMGa flow to achieve compositions between GaAs and InAs, except in the case of GaAs, where the TMIn source was turned off. The growth time of these composition-varied QWs were also scaled accordingly in order to achieve a nominal thickness of 7 nm. Another 5 s growth interruption was included after the QW growth with AsH3 left on in order to prevent As desorption from the thin QW 1. Lastly, an InP barrier shell was grown for 12 min. For the growth of MQW structure, the QW, interruption and barrier growth steps were repeated two times more

Multipolar analysis of second-harmonic generation in (111) Gallium Arsenide nanoparticles

We perform multipolar analysis of second-harmonic generation (SHG) from (111)-grown gallium arsenide (GaAs) nanoantennas and discuss its specifics. It was experimentally demonstrated that the conversion efficiency in axially-symmetric (111) GaAs nanoparticles remains constant under the polarization rotation of normally incident radiation in a wide range of particle sizes, while the SHG radiation pattern changes. We apply the analytical method based on the Lorentz lemma to explain this behaviour. The induced nonlinear current is decomposed into two rotating contributions, which are shown to generate multipoles of different parities. Thus, the total SHG intensity in the far-field is proved to be independent of the in-plane rotation of the pump polarization. Nevertheless, due to the threefold symmetry of the crystal with regard to the (111) direction, the SHG radiation pattern rotates around the polar axis repeating its shape every 60°.publishedVersionPeer reviewe

Forward and backward switching of nonlinear unidirectional emission from GaAs nanoantennas

ISSN:1936-0851ISSN:1936-086

Infrared upconversion imaging in nonlinear metasurfaces

Infrared imaging is a crucial technique in a multitude of applications, including night vision, autonomous vehicle navigation, optical tomography, and food quality control. Conventional infrared imaging technologies, however, require the use of materials such as narrow bandgap semiconductors, which are sensitive to thermal noise and often require cryogenic cooling. We demonstrate a compact all-optical alternative to perform infrared imaging in a metasurface composed of GaAs semiconductor nanoantennas, using a nonlinear wave-mixing process. We experimentally show the upconversion of short-wave infrared wavelengths via the coherent parametric process of sum-frequency generation. In this process, an infrared image of a target is mixed inside the metasurface with a strong pump beam, translating the image from the infrared to the visible in a nanoscale ultrathin imaging device. Our results open up new opportunities for the development of compact infrared imaging devices with applications in infrared vision and life sciences