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1.
Sci Rep ; 9(1): 18095, 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31792272

RESUMO

On-chip microlaser sources in the blue constitute an important building block for complex integrated photonic circuits on silicon. We have developed photonic circuits operating in the blue spectral range based on microdisks and bus waveguides in III-nitride on silicon. We report on the interplay between microdisk-waveguide coupling and its optical properties. We observe critical coupling and phase matching, i.e. the most efficient energy transfer scheme, for very short gap sizes and thin waveguides (g = 45 nm and w = 170 nm) in the spontaneous emission regime. Whispering gallery mode lasing is demonstrated for a wide range of parameters with a strong dependence of the threshold on the loaded quality factor. We show the dependence and high sensitivity of the output signal on the coupling. Lastly, we observe the impact of processing on the tuning of mode resonances due to the very short coupling distances. Such small footprint on-chip integrated microlasers providing maximum energy transfer into a photonic circuit have important potential applications for visible-light communication and lab-on-chip bio-sensors.

2.
Sci Rep ; 9(1): 259, 2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30670785

RESUMO

In recent years much effort has been made to increase the Sn content in GeSn alloys in order to increase direct bandgap charge carrier recombination and, therefore, to reach room temperature lasing. While being successful for the former, the increase of Sn content is detrimental, leading to increased defect concentrations and a lower thermal budget regarding processing. In this work we demonstrate strong photoluminescence enhancement in low Sn content Ge0.94Sn0.06 layers by implementing tensile strain. Fitting of the calculated photoluminescence spectra to reproduce our experimental results indicates a strain of ~1.45%, induced via an SiNx stressor layer, which is strong enough to transform the investigated layer into a direct bandgap semiconductor. Moreover, theoretical calculations, using the 8-band k·p model, show the advantages of using low Sn content tensile strained GeSn layers in respect to gain and lasing temperature. We show that low Sn content GeSn alloys have a strong potential to enable efficient room temperature lasers on electronic-photonic integrated circuits.

3.
Opt Express ; 26(5): 6400-6406, 2018 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-29529832

RESUMO

We demonstrate that conformal encapsulation using atomic layer deposition of GaAs nano-cavity resonator made of photonic crystal cavity prevents photo-induced oxidation. This improvement allows injecting a large quantity of energy in the resonator without any degradation of the material, thus enabling spectral stability of the resonance. We prove second harmonic and third harmonic generation over more than one decade of pump power variation, thanks to this encapsulation, with a total efficiency (ηSHG = 8.3 × 10-5 W-1 and ηTHG = 1.2 × 10-3 W-2 ) and a large net output energy for both operations (PSHGout=0.2nW and PTHGout=8pW).

4.
Opt Express ; 25(19): 23035-23044, 2017 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-29041607

RESUMO

We demonstrate low-loss GaN/AlGaN planar waveguides grown by molecular beam epitaxy on sapphire substrates. By using a proper AlGaN cladding layer and reducing surface roughness we reach <1dB/cm propagation losses at 633nm. These low propagation losses allow an efficient second harmonic generation using modal phase matching between a TM0 pump at 1260nm and a TM2 second harmonic at 630nm. A maximal power conversion of 2% is realized with an efficiency of 0.15%·W-1cm-2. We provide a modelling that demonstrates broadband features of GaN/AlGaN platform by showing second harmonic wavelengths tunability from the visible up to the near-infrared spectral region. We discuss drawbacks of modal phase matching and propose a novel solution which allows a drastic improvement of modal overlaps with the help of a planar polarity inversion. This new approach is compatible with low propagation losses and may allow as high as 100%·W-1cm-2 conversion efficiencies in the future.

5.
Opt Express ; 23(19): 24163-70, 2015 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-26406622

RESUMO

A compact (15µm × 15µm) and highly-optimized 2×2 optical switch is demonstrated on a CMOS-compatible photonic crystal technology. On-chip insertion loss are below 1 dB, static and dynamic contrast are 40 dB and >20 dB respectively. Owing to efficient thermo-optic design, the power consumption is below 3 mW while the switching time is 1 µs.

6.
Opt Express ; 21(11): 13626-38, 2013 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-23736615

RESUMO

We show that self-induced oscillations at frequencies above GHz and with a high spectral purity can be obtained in a silicon photonic crystal nanocavity under optical pumping. This self-pulsing results from the interplay between the nonlinear response of the cavity and the photon cavity lifetime. We provide a model to analyze the mechanisms governing the onset of self-pulsing, the amplitudes of both fundamental and harmonic oscillations and their dependences versus input power and oscillation frequency. Theoretically, oscillations at frequencies higher than 50 GHz could be achieved in this system.

7.
Opt Express ; 21(8): 10324-34, 2013 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-23609742

RESUMO

Collection of free carriers is a key issue in silicon photonics devices. We show that a lateral metal-semiconductor-metal Schottky junction is an efficient and simple way of dealing with that issue in a photonic crystal microcavity. Using a simple electrode design, and taking into account the optical mode profile, the resulting carrier distribution in the structure is calculated. We show that the corresponding effective free carrier lifetime can be reduced by 50 times when the bias is tuned. This allows one to maintain a high cavity quality factor under strong optical injection. In the fabricated structures, carrier depletion is correlated with transmission spectra and directly visualized by Electron Beam Induced Current pictures. These measurements demonstrate the validity of this carrier extraction principle. The design can still be optimized in order to obtain full carrier depletion at a smaller energy cost.


Assuntos
Semicondutores , Silício/química , Ressonância de Plasmônio de Superfície/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Miniaturização , Fótons
8.
Opt Lett ; 36(10): 1749-51, 2011 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-21593878

RESUMO

We propose a design for high quality factor two-dimensional (2D) photonic crystal cavities on silicon-on-insulator (SOI). A quality factor of up to 1.2×10(7) with a modal volume of 2.35(λ/n)(3) is simulated. A very high quality factor of 200,000 is experimentally demonstrated for a 2D cavity fabricated on SOI.

9.
Opt Express ; 18(23): 23965-72, 2010 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-21164743

RESUMO

We demonstrate an all-silicon photodetector working at telecom wavelength. The device is a simple metal-semiconductor-metal detector fabricated on silicon-on-insulator. A two-dimensional photonic crystal nanocavity (Q=60,000) is used to increase the response that arises from the linear and two-photon absorption of silicon. The responsivity of the detector is about 20 mA/W and its bandwidth is larger than 1 GHz.

10.
Opt Express ; 17(13): 10887-94, 2009 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-19550489

RESUMO

Midinfrared absorption can be locally measured using a detection combining an atomic force microscope and a pulsed excitation. This is illustrated for the midinfrared bulk GaAs phonon absorption and for the midinfrared absorption of thin SiO(2) microdisks. We show that the signal given by the cantilever oscillation amplitude of the atomic force microscope follows the spectral dependence of the bulk material absorption. The absorption spatial resolution achieved with microdisks is around 50 nanometer for an optical excitation around 22 micrometer wavelength.


Assuntos
Microscopia de Força Atômica/instrumentação , Microscopia de Força Atômica/métodos , Espectrofotometria Infravermelho/métodos , Absorção , Acústica , Desenho de Equipamento , Oscilometria/métodos , Semicondutores , Dióxido de Silício/química , Propriedades de Superfície
11.
Opt Express ; 17(5): 3500-7, 2009 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-19259188

RESUMO

We study the spontaneous Raman scattering in a W1 photonic crystal waveguide on silicon-on-insulator where the lower silica cladding remains. Despite the vertical asymmetry that exists in such a waveguide, we numerically and experimentally show that the propagation losses at the pump and the Stokes wavelengths remain low enough to allow a significant exaltation of the spontaneous Raman scattering. In particular, we observe a reshaping of the Raman spectrum and a more than ten-fold enhancement of the Raman scattering efficiency in a W1 photonic crystal waveguide as compared to a single-mode ridge waveguide.

12.
Opt Express ; 16(16): 12278-89, 2008 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-18679505

RESUMO

Photonic crystals exhibiting a photonic band gap in both TE and TM polarizations are particularly interesting for a better control of light confinement. The simultaneous achievement of large band gaps in both polarizations requires to reduce the symmetry properties of the photonic crystal lattice. In this letter, we propose two different designs of two-dimensional photonic crystals patterned in high refractive index thin silicon slabs. These slabs are known to limit the opening of photonic band gaps for both polarizations. The proposed designs exhibit large complete photonic band gaps: the first photonic crystal structure is based on the honey-comb lattice with two different hole radii and the second structure is based on a "tri-ellipse" pattern in a triangular lattice. Photonic band gap calculations show that these structures offer large complete photonic band gaps deltaomega/omega larger than 10% between first and second photonic bands. This figure of merit is obtained with single-mode slab waveguides and is not restricted to modes below light cone.


Assuntos
Projeto Auxiliado por Computador , Modelos Teóricos , Óptica e Fotônica/instrumentação , Refratometria/instrumentação , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Fótons
13.
Phys Rev Lett ; 99(21): 217404, 2007 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-18233255

RESUMO

We show that we can measure the room temperature ultraweak absorption of a single buried semiconductor quantum dot. This is achieved by monitoring the deformation field induced by the absorption of midinfrared laser pulses and locally detected with an atomic force microscope tip. The absorption is spectrally and spatially resolved around lambda approximately 10 microm wavelength with 60 nm lateral resolution (lambda/150). The electronic S-D intersublevel absorption of a single quantum dot is identified around 120 meV and exhibits a homogeneous linewidth of approximately 10 meV at room temperature.

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