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The progress of 1.3- and 1.5-μm waveband wafer-fused VCSELs is reported. The emission of single mode power of 6 - 8 mW at room temperature and up to 3 mW at 80°C were demonstrated. 10-Gb/s full wavelength-set VCSEL devices for CWDM systems with high yield and Telcordia-reliability were industrially manufactured. By increasing the compressive strain in the QWs and reducing the cavity photon life time the modulation bandwidth was increased to 11.5 GHz, and large-signal data transmission experiments show error-free operation and open eye diagrams from 25 to 35 Gb/s in both B2B and after 10-km, respectively.

Long wavelength (LW) vertical cavity surface emitting lasers (VCSELs) are important low cost and low power consumption sources for optical interconnects in data centers, sensing and spectroscopy [1,2]. We discuss here the recent progress in the design, fabrication and industrialization of such devices made by using wafer fusion, which allows integration of GaAs-based distributed Bragg reflectors (DBRs) with InP-based active structures and an independent optimization of the mirror and active cavity properties before the fusion. Both the GaAs-based mirrors and InP-based optical gain structures are grown by metalorganic vapor phase epitaxy (MOVPE). The VCSEL structure comprises an InP-based active region with 5 to 6 InAlGaAs compressively strained quantum wells (QWs) as the gain medium and tunnel junction (TJ) aperture for current and optical confinement, double-fused to two GaAs/AlGaAs-based Bragg mirrors (Fig.1a). By epitaxial growth, device design and processing optimization 1.3- and 1.5μm waveband VCSELs emitting single mode power of 6–8-mW at room temperature and up to 3-mW at 80°C were demonstrated (Fig.1b) [3,4]. Moreover, industrially manufactured 10-Gb/s full CWDM wavelength-set VCSEL devices for coarse wavelength division multiplexing systems with high yield and Telcordia-reliability have been developed [5–6].

MOVPE epitaxial growth and design optimisation of 1.5 μm vertical cavity surface emitting lasers (VCSELs) for high power, single mode and high-temperature operation are presented. The VCSEL structure comprises a strain-compensated InAlGaAs MQW active region, a p ++ /n ++ In(Al)GaAs tunnel junction and top and bottom AlGaAs/GaAs fused distributed Bragg reflectors. All epitaxial layers were grown by low-pressure MOVPE in nitrogen atmosphere. Excellent optical and electrical confinement is obtained by wafer-bonding of the top mirror on tunnel junction pre-etched mesas. Devices with 7 μm aperture show single transverse mode CW operation up to 4 mW at room temperature, with 30–35 dB side-mode suppression ratio and a far field divergence angle of 9°. At 85 °C, a record single mode high emission power up to 1.7 mW is demonstrated.

We have combined atomic force microscopy (AFM) and 2D+1 Monte-Carlo simulations to investigate the formation of local potential minima in self-ordered AlGaAs/GaAs V-groove quantum wires. In order to determine the origin of these potential fluctuations along the wire axis in the sub-micrometer range, we studied by AFM the morphology of V-grooved substrates at different stages of processing and growth. Monte-Carlo simulations are used to study the influence of the growth kinetics on the self-limiting profile in disordered V grooves. Our model evidences a re-entrant mechanism in which the sidewalls roughness induces monolayers thickness fluctuations along the wire axis. The influence of the growth conditions on the quantum wire disorder is discussed.

We report the fabrication and the optical properties of dense arrays of strained InGaAs/GaAs V-groove quantum wires (QWRs) embedded in wavelength size planar Bragg microcavities, made using a two-step organometallic chemical vapor deposition (OMCVD). Growth front evolution and top surface morphology of GaAs on the corrugated substrate were investigated as a function of the growth temperature (550–625°C) and the pitch of the V-groove grating (3–0.25 μm). Based on these studies, a growth temperature of 550°C and a grating pitch of 0.25 μm were selected to achieve sizes compatible with simultaneous quantum confinement for electron (≈10 nm wide wires) and photon (≈0.25 μm thick cavities) states. Reference arrays of uniform, nanometer-size, crescent-shaped, InGaAs QWRs with densities up to 4QWRs/μm were realized, exhibiting a narrow (8 meV) and intense emission from one-dimensional excitonic states at low temperature. Similar QWRs were then successfully embedded in planar microcavities, showing brighter (×50) emission with a strongly reduced linewidth (1 meV) due to resonant coupling between the wire emission and the microcavity modes.

We demonstrate 2-mum wavelength, wafer-fused In(Al)GaAs-InP-AlGaAs-GaAs vertical-cavity surface-emitting lasers (VCSELs) emitting single-mode power of 0.5 mW at room temperature with a threshold current of 4 mA and sidemode suppression ratio of over 30 dB. These devices can be continuously tuned with current by 5 nm without mode hopping, with a tuning rate of 0.31 nm/mA. These features demonstrate the potential of these long wavelength VCSELs for gas sensing and other optical spectroscopy applications.

We have studied the capabilities of chemical beam epitaxy (CBE) to produce high-gain media for long-wavelength (1.5 mu m) vertical cavity surface emitting lasers (VCSELs). Using a parameter pair of low growth temperature and small V/III ratio the integration of up to 15 highly strained (1.78%) InAsP quantum wells (QWs) into a periodic gain structure (PGS) is successfully demonstrated. In this work we present data of atomic force microscopy (AFM), X-ray diffraction, reflectivity and electro-luminescence measurements that prove the very good structural and optical quality of this CBE grown PGS. As an alternative to conventional multi quantum well(MQW) systems as active layers, a high-performance PGS may be used in a VCSEL structure to reduce the very strict requirements on the InP-based distributed Bragg reflectors (DBRs) or to increase the achievable output power. Due to the use of thickness-reduced InP-based DBRs in conjunction with a PGS as the active region the fabrication of fully epitaxial grown long-wavelength VCSELs might also be possible with CBE. (C) 1998 Elsevier Science B.V. All rights reserved.

The development of the 10GBASE-LX4 communication standard for aggregated 10-Gb/s rates feeds the need for low-cost laser sources in the 1275-1350-nm wavelength range operating at modulation rates of 3.125 Gb/s. We present comprehensive characterization of wafer fused vertical-cavity surface-emitting lasers with characteristics that meet the IEEE802.3ae specification for 10GBASE-LX4. These include output power greater than 1.5 mW up to 80degC, wavelength around 1340 nm, single-mode emission and modulation at 3.125 Gb/s, and wide open eyes with rise and fall times below 100 ps up to 70degC

Reference LPN-ARTICLE-1997-009doi:10.1016/S0022-0248(96)00955-4View record in Web of Science Record created on 2008-02-29, modified on 2017-05-12

High-performance vertical-cavity surface-emitting lasers (VCSELs) emitting in the 1310-nm waveband are fabricated by bonding AlGaAs-GaAs distributed Bragg reflectors on both sides of a InP-based cavity. A 2-in wafer bonding process is optimized to produce very good on-wafer device parameter uniformity. Carrier injection is implemented via double intracavity contact layers and a tunnel junction. A 1.2-mW single-mode output power is obtained in the temperature range of 20/spl deg/C-80/spl deg/C. Modulation capability at 3.2 Gb/s is demonstrated up to 70/spl deg/C. Overall VCSEL performance complies with the requirements of the 10 GBASE-LX4 IEEE.802.3ae standard, which opens the way for novel applications of VCSELs emitting in the 1310-nm band.

When InP is grown by chemical beam epitaxy on substrates patterned with ridges oriented along [110] with (111)B sidewall planes, the migration of In species on the surface changes direction with growth temperature. The movement is from the ridge to the valley through the sidewall above 505 degrees C, and from the sidewall to the ridge below 495 degrees C. By using this specific growth behavior, we have obtained a triangular prism-shaped buried heterostructure with a narrow active region. We also present an estimation of the growth temperature dependence of the diffusion length on each plane and propose a model explaining the above migrations.

We demonstrate widely tunable InAlGaAs-InP-AlGaAs-GaAs optically pumped vertical-cavity surface-emitting lasers operating in the 1.55-/spl mu/m waveband. The tuning range of 32 nm is achieved by applying a low tuning voltage of 4 V. Maximum single-mode output power of 2 mW with less than 1.5-dB power variation over the whole tuning range and side-mode suppression ratio in excess of 30 dB have been obtained.

We demonstrate 1.5-/spl mu/m waveband wafer-fused InGaAlAs-InP-AlGaAs-GaAs vertical-cavity surface-emitting lasers (VCSELs) emitting high single-mode power of 1.5 mW at room temperature with sidemode suppression ratio of over 30 dB and a full-width at half-maximum far field angle of 9/spl deg/. These devices have thermal resistance value below 1.5 K/mW and are emitting 0.2 mW at 70/spl deg/C. VCSELs with a wavelength span of 40-nm emission are produced from the same active cavity material, which shows the potential of realizing multiple-wavelength VCSEL arrays.

The dynamics of acoustic vibrations in terahertz quantum cascade laser structures (THz-QCLs) is studied by means of femtosecond pump-probe spectroscopy. The phonon modes are characterized by the folding of the acoustic dispersion into an effective reduced Brillouin zone. An accurate identification of this dispersion allows the sample structure and periodicity to be determined with high precision on the order of 0.1%. By temperature tuning the energy of the electronic levels of the system and performing wavelength dependent measurements, we are able to study the impulsive resonant generation and detection of coherent acoustic phonon modes. These results are supported by simulations of the electronic system that well explain the experimental observations. The effects of interface (IF) roughness on coherent acoustic phonon spectra are clearly observed for equal nominal THz-QCL structures but with different interface qualities. Fil: Bruchhausen, Axel Emerico. University of Konstanz. Department of Physics and Center for Applied Photonics; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lloyd Hughes, James . University of Oxford; Reino Unido Fil: Hettich, Mike . University of Konstanz. Department of Physics and Center for Applied Photonics; Alemania Fil: Gebs, Raphael . University of Konstanz. Department of Physics and Center for Applied Photonics; Alemania Fil: Grossmann, Martin . University of Konstanz. Department of Physics and Center for Applied Photonics; Alemania Fil: Ristow, Oliver . University of Konstanz. Department of Physics and Center for Applied Photonics; Alemania Fil: Bartels, Albrecht . University of Konstanz. Department of Physics and Center for Applied Photonics; Alemania Fil: Fischer, Milan . Institute of Quantum Electronics; Suiza Fil: Beck, Mattias . Institute of Quantum Electronics; Suiza Fil: Scalari, Giacomo . Institute of Quantum Electronics; Suiza Fil: Faist, Jérôme . Institute of Quantum Electronics; Suiza Fil: Rudra, Alok . Ecole Polytechnique Federale de Lausanne; Suiza Fil: Gallo, Pascal . Ecole Polytechnique Federale de Lausanne; Suiza Fil: Kapon, Eli . Ecole Polytechnique Federale de Lausanne; Suiza Fil: Dekorsy, Thomas . University of Konstanz. Department of Physics and Center for Applied Photonics; Alemania

The effect of the miscut angle of vicinal substrate on the optical and morphological properties of GaAs/AlxGa1-xAs quantum wells grown by metalorganic vapor phase epitaxy is studied by means of photoluminescence (PL) and atomic force microscopy. Within small changes of the miscut angle, we observe strong variations of the PL linewidth, energy, and lineshape, as well as transitions between the morphology of the sample's surface and interface. The relation between these features is discussed, and the particular case of structures exhibiting high optical quality is studied in more detail. Moreover, the role of growth dynamics is highlighted by observing the evolution of the hetero-interfaces during growth interruption.

The authors report the growth behavior of the InP, InGaAs and InGaAsP on non-planar InP substrates where ridges were formed with (111)A, (211)A, (111)B and (551) sidewall planes. All three materials grow uniformly on the whole patterned surface with (111)A and (211)A sidewall planes. They grow separately on the plateau and in the valley for the other two structures. The growth front of the InGaAs films is always rippled near the sidewalls, indicating large deviations from lattice-matched composition in these areas, while the growth front in the case of the InP and InGaAsP films remains smooth. Single-step growth of buried double heterostructures with a 1 mu m wide rib is realized for the structures with both (111)B and (551) sidewall planes. The growth mechanisms responsible for the observed features are discussed.

We report on the first observation of both confined optical phonons and interface phonons in a single strained InAs quantum well grown on InP. Quasi resonant Raman measurements allow for the observation of interface modes. Informations about the mismatch induced strain in the InAs layer are obtained. The effect of the strain and the confinement on the longitudinal and transverse optical InAs modes are estimated.

Site-controlled quantum-wire photonic-crystal microcavity laser is experimentally demonstrated using optical pumping. The single-mode lasing and threshold are established based on the transient laser response, linewidth narrowing, and the details of the non-linear power input-output charateristics. Average-power threshold as low as similar to 240 nW (absorbed power) and spontaneous emission coupling coefficient beta similar to 0.3 are derived. (C) 2009 Optical Society of America

High spontaneous-emission coupling and low-threshold lasing is achieved in semiconductor photonic-crystal cavities using short quantum wires. Lasing is established and characterized based on the linewidth narrowing and time-resolved photon dynamics.

The indium desorption rates from InGaAs and InAlAs grown on InP substrates have been measured by wedge transmission electron microscopy as a function of the growth temperature. Desorption becomes significant at 545-degrees-C for both materials. No automatching effects could be observed under the growth conditions of the experiment. The bandgap of In(y)Al1-yAs has been measured at 77 K as a function of the indium content. The composition and the strain have been measured by four-crystal high resolution X-ray diffraction with symmetrical (004) and assymmetrical (115 +/-) Bragg reflections. The intrinsic bandgap follows the relation E(g)(y) = 2.774 - 2.411 y and the strained material the relation E(gs)(y) = 0.671 + 5.236y-6.929y2.

Splitting of mode wavelength and loss are observed in coupled photonic-crystal cavities. The characteristics of loss splitting are shown to have important impact on the optical energy transfer between such coupled resonators.

We demonstrate 2-mum wavelength, wafer-fused InGa(Al)As/InP-AlGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) emitting single-mode power of 0.5 mW at room-temperature with a threshold current of 4 mA and side-mode suppression ratio of over 30 dB. Emission wavelength can be continuously tuned with current by ~5 nm without mode hopping with a tuning rate of 0.31 nm/mA. These features demonstrate the long wavelength VCSELs potential for gas sensing and other optical spectroscopy applications.

We demonstrate double wafer-fused 1.3 and 1.5 μm VCSELs showing record high single mode power up to 75°C, as well as polarization stability, modulation speed up to 10 Gb/s, and accurate wavelength selection capabilities.

High performance vertical cavity surface emitting lasers (VCSELs) emitting in the 1310 nm waveband are fabricated by bonding AlGaAs/GaAs distributed Bragg reflectors (DBRs) on both sides of a InP-based cavity containing 5 InAlGaAs quantum wells using the localized wafer fusion technique. A tunnel junction structure is used to inject carriers into the active region. Devices with 7 mm aperture produce single mode emission with 40 dB side-mode suppression ratio. Maximum single mode output power of 1.7 mW is obtained in the temperature range of 20-70dC. Modulation capability at 3.2 Gb/s is demonstrated both at room temperature and 70dC with rise time and fall time values of eye diagrams bellow 120 ps. Overall device performance complies with the requirements of 10 GBASE-LX4 IEEE.802.3ae standard.

Wafer fused InGaAlAs/AlGaAs VCSEL emitting in the vicinity of 1325 nm with InAlGaAs-based tunnel junction injection show record high 1.2 mW single mode output and 40 dB side-mode suppression ratio in the 20-80/spl deg/C temperature range and. good on-wafer device parameter uniformity.

We investigated experimentally 1D and 2D arrays of coupled L3 photonic crystal cavities. The optical modes of the coupled cavity arrays are fed by a site-controlled quantum wire light source. By performing photoluminescence measurements and relying on near-field calculation of the cavitiy modes, we evidence optical coupling between the cavities as well as supermode delocalization. In particular, for small cavity separations, fabrication induced disorder effects are shown to be negligible compared to optical coupling between cavities. (C) 2013 Optical Society of America

We have demonstrated InGaAsP/AlGaAs double fused 1.5 micrometers multiple wavelength vertical cavity lasers and arrays in which element definition is obtained by localized fusion. Laser elements emit in continuous wave under electrical and optical pumping. Multiple wavelength single element VCSELs have been fabricated in the same batch taking advantage of layer thickness nonuniformity of InGaAsP/InP material close to the edge of the wafer. To obtain multiple wavelength arrays a controllable cavity length variation using anodic oxidation has been performed. The wavelength span in an 8 by 1 laser array is 10 nm. Single mode operation with more than of 40 dB side mode suppression ratio is characteristic for laser elements in the array.

We have evaluated the resonant photodetection characteristics of long wavelength double fused InGaAsP/AlGaAs vertical cavity lasers. Using VCSEL structures fabricated by the localized fusion technique for laser generation, light detection is also possible in open circuit, short circuit and forward biased (FB) regimes. The wavelength selectivity of the detection increases with driving current in FB regime. Detection spectrum with FWHM as low as 0.02 nm is demonstrated in the FB regime at currents above threshold. Investigated structures emit and detect light with high spectral selectivity and may be very useful as multifunctional elements for signal generation and detection in wavelength division multiplexing (WDM) systems.

We have studied the effect of growth interruptions on 2‐monolayers‐thick InAs/InP strained quantum wells (QW) grown by chemical beam epitaxy. The main feature is the formation of up to 8‐monolayers‐thick InAs islands during As2 annealing of the QW. Their formation is characterized by a two to three dimensional transition of the reflection high‐energy electron diffraction pattern and multiple‐lines photoluminescence spectra. An increase of a short range roughness at the InP‐InAs interface due to As2 annealing of InP is also observed.

Coupling of L-type photonic-crystal (PhC) cavities in a geometry that follows inherent cavity field distribution is exploited for demonstrating large mode splitting of up to similar to 10-20 nm (similar to 15-30 meV) near 1 mu m wavelength. This is much larger than the disorder-induced cavity detuning for conventional PhC technology, which ensures reproducible coupling. Furthermore, a microlaser based on such optimally coupled PhC cavities and incorporating quantum wire gain medium is demonstrated, with potential applications in fast switching and modulation. (C)2011 Optical Society of America

A transition from discrete optical modes to 1D photonic bands is experimentally observed and numerically studied in planar photonic-crystal (PhC) L(N) microcavities of length N. For increasing N the confined modes progressively acquire a well-defined momentum, eventually reconstructing the band dispersion of the corresponding waveguide. Furthermore, photon localization due to disorder is observed experimentally in the membrane PhCs using spatially resolved photoluminescence spectroscopy. Implications on single-photon sources and transfer lines based on quasi-1D PhC structures are discussed.

Coupling between photonic-crystal defect microcavities is observed to result in a splitting not only of the mode wavelength but also of the modal loss. It is discussed that the characteristics of the loss splitting may have an important impact on the optical energy transfer between the coupled resonators. The loss splitting — given by the imaginary part of the coupling strength — is found to arise from the difference in diffractive out-of-plane radiation losses of the symmetric and the antisymmetric modes of the coupled system. An approach to control the splitting via coupling barrier engineering is presented.

Wafer-fused InGaAlAs/AlGaAs vertical cavity surface emitting lasers with InAlGaAs-based tunnel junction injection have shown record high 0.7 mW singlemode output power in the 10-80/spl deg/C temperature range. Single transverse-mode operation with 35 dB sidemode suppression and low divergence beam with 9/spl deg/ half width at half maximum has been measured on devices with 7 /spl mu/m aperture.

Reference LPN-ARTICLE-1998-004doi:10.1049/el:19981148View record in Web of Science Record created on 2008-02-29, modified on 2017-12-03

1.52 µm double fused InGaAsP/AlGaAs vertical cavity surface emitting lasers with in situ built-in lateral current confinement were fabricated using a localised wafer fusion process. A threshold current of 2.5 mA at 4 V was obtained for devices with a 10 × 10 µm2 current aperture. These devices operate CW up to 30°C. The width of the dominant mode is less than 0.1 nm and the sidemode suppression ratio is 30 dB.

Reference LPN-ARTICLE-2002-003doi:10.1016/S0022-0248(01)02297-7View record in Web of Science Record created on 2008-02-29, modified on 2017-05-12

The authors present low voltage barrier p-InP/p-GaAs junctions obtained by localised fusion which facilitates a better evacuation of absorbed gases and native oxides from the fused interface. Using this approach InGaAs/lnGaAsP/InP edge emitting lasers fused to p-GaAs were realised for the first time, showing better parameters than as-grown diodes. The presented results prove that localised fusion is a suitable tool for achieving additional lateral current confinement, which may be important for a wide variety of other device applications.

A high-reflectance GaInP/GaAs distributed Bragg reflector (DBR) was grown by chemical beam epitaxy (CBE). The mirror consists of 40 pairs of alternating layers and was designed for a centre wavelength of 980 nm, resulting in a total thickness of 5.8 mum. Highly stable growth conditions led to a maximum reflectance of 0.99 and to a variation in the centre wavelength of only 5 nm over the 2'' (50.8 mm) wafer. Transmission electron microscopy and X-ray diffraction measurements confirmed the vertical uniformity and the crystallographic quality of the sample.

An experimental method for accurate measurements of the reflectivity spectrum of mirrors is presented. It combines the noise reduction obtained with multiple beam reflections on two identical mirrors; high-beam quality, owing to the use of single-mode optical fibers; and high immunity against intensity variations of the beam. This method is demonstrated for characterizing a 30-period GaAs/Al(0.65)Ga(0.35)As distributed Bragg reflector designed for long-wavelength vertical-cavity surface-emitting lasers. Its peak reflectivity is found to be 99.43 ? 0.04% at 1.562 mum, and an optical absorption coefficient of alpha = 36 ? 6 cm(-1) is derived. The peak internal reflectivity of this distributed Bragg reflector used as the top mirror in a wafer-fused vertical-cavity surface-emitting laser is calculated to be 98.87 ? 0.12%, and the transmission is 0.28%.

Strong optical confinement implemented with 2D photonic-crystal (PhC) microcavities provides a powerful tool for controlling the features of light-matter interaction. Combined with nanostructures such as quantum wells, quantum wires (QWRs) or quantum dots, the PhC cavities — efficiently controlling spontaneous emission [1] — are envisaged to bring superior semiconductor-laser performance [2], which could be exploited for applications in low-power-consumption integrated optoelectronics. Furthermore, inter-cavity optical coupling may allow for optimizing the laser output power [3] and realizing ultra-fast switching devices [4]. Here, we present experimental and numerical studies of directly coupled L 3 -type PhC microcavities that employ monolithically embedded site-controlled QWRs acting as local internal light sources. Using microphotoluminescence (PL) experiments [5], it is shown that such PhC system supports coupled modes with distinct resonant wavelengths and delocalized optical fields. It is also demonstrated that the cavity losses of these modes may “split” as well, in general. Furthermore, we demonstrate single-mode QWR-PhC microlasers. Low thresholds (∼1 µW) and relatively high spontaneous-emission coupling factors (β ∼ 0.3) are achieved. Lasing is established based on power-dependent linewidth narrowing [6] and time-resolved photon dynamics [7]. This work provides grounds for the development of more complex PhC systems for experiments in quantum physics [8] and microlasers [4].

We have evaluated the structure of high-reflectivity InP/InGaAsP distributed Bragg reflectors grown by chemical-beam epitaxy at a growth rate of 3 mu m/h. Transmission electron microscopy combined with electron energy loss spectroscopy indicate lateral fluctuations in the GaInAsP alloy composition, clearly visible in the 490-510 degrees C growth temperature range, but less perceptible between 460 and 480 degrees C. In the higher temperature range, the modulation in composition shows a higher frequency along the [1 (1) over bar 0] direction than along [1 1 0].

We propose and investigate a new type of photonic crystal (PhC) cavity for integrated quantum photonics, which provides tailored optical modes with both confined and extended spatial components. The structures consist of elongated PhC cavities in which the effective index of refraction is varied quasi-linearly along their axis, implemented by systematic lateral shifts of the PhC holes. The confined modes have approximately Airy-function envelopes, exhibiting single peaks and extended tails, which is useful for optimizing single photon extraction and transmission in integrated quantum photonic devices. The measured spectrally resolved near-field patterns of such devices show the expected spatial and resonance wavelength behavior, in agreement with numerical simulations of the Airy-Bloch modes. The effects of fabrication-induced disorder on the mode features are also analyzed and discussed. Selective excitation of specific Airy-Bloch modes using integrated, site-controlled quantum dots as localized light sources is demonstrated. Based on the tilted-potential cavity, multiple-QD single photon emitters exploiting wavelength division multiplexing are proposed. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement