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Near-infrared (NIR) spectroscopy is widely used for the classification of materials and the quantification of their properties. Today, there is a high demand for extending the use of this technique to portable applications, and eventually, the integration with consumer appliances and smartphones. To reach this goal, the overall size of the NIR sensor, its production cost, robustness, and resistance to vibrations are of particular importance. This paper describes an approach to spectral sensing in the NIR (850–1700 nm) using a handheld sensor module based on a fully integrated multipixel detector array with a footprint of around 2×2 mm2. The capabilities of the spectral sensor module were recently evaluated in two application cases: Quantification of the fat percentage in raw milk and the classification of plastic types. Fat quantification was achieved with a root mean square error (RMSE) of prediction of 0.14% and classification of plastic types was achieved with a prediction accuracy on unknown samples of 100%. The results demonstrate the feasibility of the direct NIR sensing approach used by the integrated sensor, which has potential to be used in a variety of applications.

Butt-joint regrowth is widely used in photonic integration, but it has been challenging to break the density-quality tradeoff due to the edge growth rate enhancement (GRE) effect. In this work, we propose a scheme to circumvent this tradeoff by using large regrowth masks whose centers are exposed to epi-growth for neutralization of the excessive species. With the GRE under control, epi-stacks with arbitrarily large sizes supporting dense arrays can be butt-joint integrated with minimal compromise to their epitaxy quality. In our experiment, multi-quantum-well-based material of an exceptionally large area of 0.5 × 1.7 mm2 was epitaxially integrated with passive InP material on the same wafer. A more than 20 × reduction in edge topology compared to conventional methods was achieved.

We present a novel approach to NIR spectral sensing using a handheld module based on a miniaturized integrated detector array. Applicability of the sensor is demonstrated in monitoring moisture in grains and classification of plastics.

We demonstrate a compact and robust near-infrared (900-1700nm) spectral sensor consisting of 16 resonant-cavity-enhanced photodetectors. We achieve a tunable spectral response with narrow linewidth and high responsivity and demonstrate the sensing performance on various applications.

Silicon (Si) donors in GaAs have been the topic of extensive studies since Si is the most common and well understood n-type dopant in III-V semiconductor devices and substrates. The indirect bandgap of AlAs compared to the direct one of GaAs leads to interesting effects when introducing Si dopants. Here we present a study of cross-sectional scanning tunneling microscopy (X-STM) and density functional theory (DFT) calculations to study Si donors in AlAs at the atomic scale. Based on their crystal symmetry and contrast strengths, we identify Si donors up to four layers below the (110) surface of AlAs. Interestingly, their short-range local density of states (LDOS) is very similar to Si atoms in the (110) surface of GaAs. Additionally we show high-resolution images of Si donors in all these layers. For empty state imaging, the experimental and simulated STM images based on DFT show excellent agreement for Si donor up to two layers below the surface.

In this talk we will present recent process on the integration of nano-opto-electro-mechanical sensors with photonic circuits and optical read-out, showing a route towards fully-integrated optical sensing.

We present an efficient and flexible method to realize micro- and nano-optical structures on the tip of optical fibers. We demonstrate this approach for a fiber-tip sensor consisting of a photonic crystal (PhC) structure in a semiconductor membrane on the cleaved facet of a telecom fiber. The PhC structure is fabricated on a wafer by lithography and etching and then transferred to the fiber facet by a simple mechanical pickup process through an opening in the substrate, without the need for adhesives or a micromanipulator. Due to its reliability, scalability, and the use of wafer-scale fabrication methods, this process increases the possibilities for fiber-tip applications at the industrial level. With the fabricated fiber tip sensors, we demonstrate sensing of the refractive index and temperature, with resonance wavelength shifts of 120 nm/RIU and 95 pm/K, respectively.

We present a novel method to fabricate fiber-tip sensors. Using high-throughput semiconductor fabrication methods combined with a simple fiber-attachment scheme, we can mass-produce the sensors, preserving their surface unaltered. We experimentally demonstrate the sensor performance.

Nanoscale light sources using metal cavities have been proposed to enable high integration density, efficient operation at low energy per bit and ultra-fast modulation, which would make them attractive for future low-power optical interconnects. For this application, such devices are required to be efficient, waveguide-coupled and integrated on a silicon substrate. We demonstrate a metal-cavity light-emitting diode coupled to a waveguide on silicon. The cavity consists of a metal-coated III–V semiconductor nanopillar which funnels a large fraction of spontaneous emission into the fundamental mode of an InP waveguide bonded to a silicon wafer showing full compatibility with membrane-on-Si photonic integration platforms. The device was characterized through a grating coupler and shows on-chip external quantum efficiency in the 10−4–10−2 range at tens of microamp current injection levels, which greatly exceeds the performance of any waveguide-coupled nanoscale light source integrated on silicon in this current range. Furthermore, direct modulation experiments reveal sub-nanosecond electro-optical response with the potential for multi gigabit per second modulation speeds., Despite much progress, nanoscale light sources suitable for photonic integration are lacking. Here, the authors present a metal-cavity nanopillar LED on a silicon substrate working at telecommunications wavelengths, which demonstrates compatibility with membrane-on-Si photonic integration platforms.

In this paper, we present significant reductions of optical losses and contact resistances in AgGe-based ohmic contacts to InP membranes. Due to the high solubility of Si in InGaAs and InGaAsP, heavily doped n-type contact layers are grown on InP wafers. This high doping concentration gives rise to annealing-free ohmic contacts and low contact resistances at the level of $10^{-7}\ \Omega\ \textrm{cm}^{2}$ . It also leads to strong band-filling effects in InGaAs and InGaAsP, which result in low optical absorption losses in the contact layer. Combined with the low optical loss of AgGe, a massive reduction of the propagation loss in membrane waveguides is observed compared with other existing solutions. An additional advantage is the minimal influence of thermal treatments during the processing, leading to very stable high-performing contacts.

The III-V semiconductor InGaAs is a key material for photonics because it provides optical emission and absorption in the 1.55 μm telecommunication wavelength window. However, InGaAs suffers from pronounced nonradiative effects associated with its surface states, which affect the performance of nanophotonic devices for optical interconnects, namely nanolasers and nanodetectors. This work reports the strong suppression of surface recombination of undoped InGaAs/InP nanostructured semiconductor pillars using a combination of ammonium sulfide, (NH4)2S, chemical treatment and silicon oxide, SiOx, coating. An 80-fold enhancement in the photoluminescence (PL) intensity of submicrometer pillars at a wavelength of 1550 nm is observed as compared with the unpassivated nanopillars. The PL decay time of ∼0.3 μm wide square nanopillars is dramatically increased from ∼100 ps to ∼25 ns after sulfur treatment and SiOx coating. The extremely long lifetimes reported here, to our knowledge the highest reported to date for undoped InGaAs nanostructures, are associated with a record-low surface recombination velocity of ∼260 cm/s. We also conclusively show that the SiOx capping layer plays an active role in the passivation. These results are crucial for the future development of high-performance nanoscale optoelectronic devices for applications in energy-efficient data optical links, single-photon sensing, and photovoltaics.

Summary form only given. In this work, we report a remarkable suppression of the surface recombination rates in passivated III-V undoped InGaAs nanopillars on InP (inset of Fig. 1a). The surface passivation comprises ammonium sulfide, (NH4)2S, chemical treatment followed by encapsulation with a 50 nm layer of SiOx by plasma-enhanced chemical vapor deposition performed at 300°C. Before passivation, fabricated nanopillars with -300 nm lateral width, d, show a very poor photoluminescence (PL) emission (blue curve in Fig. 1a). The corresponding carrier dynamics, measured by time-correlated single-photon counting, Fig 1b, reveal an extremely short lifetime of ~130 ps, related to the well-known strong surface recombination velocity at InGaAs surfaces [3]. After the sulfur treatment followed by SiOx, we observe a substantial increase by almost two orders of magnitude of the PL intensity (red curve in Fig. 1a), while the carrier lifetime increases by more than two orders of magnitude to a value ~23 ns, red curve in Fig 1b. The estimated surface recombination velocity, S, decreases from about 2×104 cm/s in the untreated nanopillars down to around 260 cm/s (inset of Fig. 1b). To our knowledge, this is a record low value in undoped InGaAs semiconductors. Most importantly, our passivation studies reveal that the SiOx capping layer not only protects the pillars' sidewalls against oxidation, as reported in [5], but actively takes part in the passivation process, a result never previously reported.

Metallic-Cavity lasers or plasmonic nanolasers of sub-wavelength sizes have attracted great attentions in recent years, with the ultimate goal of achieving continuous wave (CW), room temperature (RT) operation under electrical injection. Despite great efforts, a conclusive and convincing demonstration of this goal has proven challenging. By overcoming several fabrication challenges imposed by the stringent requirement of such small scale devices, we were finally able to achieve this ultimate goal. Our metallic nanolaser with a cavity volume of 0.67{\lambda}3 ({\lambda}=1591 nm) shows a linewidth of 0.5 nm at RT, which corresponds to a Q-value of 3182 compared to 235 of the cavity Q, the highest Q under lasing condition for RT CW operation of any sub-wavelength laser. Such record performance provides convincing evidences of the feasibility of RT CW metallic nanolasers, thus opening a wide range of practical possibilities of novel nanophotonic devices based on metal-semiconductor structures., Comment: This paper has been withdrawn by the author after the final publication in Optics Express, 21, 4728(2013)

Progress on the development of a long wavelength (∼2 µm) generic monolithic photonic integration technology on indium phosphide substrate and a novel concept of a tunable laser realized as a photonic integrated circuit using such technology are presented. Insights into the development of active and passive waveguide structures which are used to define a limited set of on-chip functionalities in the form of building blocks will be given. A novel tunable laser was proposed and designed using such predefined set of basic building blocks. The laser geometry features an intra-cavity wavelength tuning mechanism based on asymmetric Mach-Zehnder interferometers in a nested configuration. The photonic integrated circuit chip was fabricated within the first long wavelength multi-project wafer run. The experimental evaluations of the fabricated device show a record tuning range of 31 nm around 2027 nm and successful measurements of a 0.86 GHz wide absorption line of carbon dioxide. These results provide a demonstration of a fully functional photonic integrated circuit operating at wavelengths that are much longer than those in the typical telecommunication windows as well as the use of indium phosphide based generic photonic integration technologies for gas sensing applications.

In this paper, measurements and analysis of the small-signal net modal gain of single-layer InAs/InP(100) quantum-dot (QD) optical amplifiers are presented. The amplifiers use only a single layer of InAs QDs on top of a thin InAs quantum well. The devices have been fabricated using a layer stack that is compatible with active–passive integration scheme, which makes further integration possible. The measurement results show sufficient optical gain in the amplifiers and can thus be used in applications such as lasers for long-wavelength optical coherence tomography and gas detection. The temperature dependence of the modal gain is also characterized. An existing rate-equation model was adapted and has been applied to analyze the measured gain spectra. The current injection efficiency has been introduced in the model to obtain a good fit with the measurement. It is found that only a small portion ($sim$1.7%) of the injected carriers is actually captured by the QDs. The temperature dependence of several parameters describing the QDs is also discovered. The mechanisms causing the blue shift of peak gain as the current density increases and the temperature changes are analyzed and discussed in detail.

In this paper, we present the design, fabrication, and characterization of two monolithically InP-based integrated electro-optically tunable filters. The combination of these filters can be used to achieve a filter with a narrow passband and a large free spectral range. These filters are designed to be used in an integrated tunable laser source in the 1600-1800 nm wavelength region using active-passive integration technology. The fact that these filters worked successfully shows that this integration technology, originally designed to be used around 1550 nm wavelength, can also be used successfully in the 1600-1800 nm wavelength region without a large penalty in performance. The two filters, a high-resolution arrayed waveguide grating-type filters and a low-resolution multimode interferometer-tree-type filter are made tunable using 5 mm long electro-optic phase modulators in the arms of the waveguide arrays. Measurements show that these filters can be tuned over a wavelength range of more than 100 nm with an accuracy of 0.1 nm (1% of the free spectral range) for the high-resolution filter and an accuracy of 9 nm (4% of the free spectral range) for the low-resolution filter.

We report the growth, device fabrication, and performance of stacked InAs/InGaAsP/InP (1 0 0) quantum dots (QDs) in telecom lasers. Wavelength tuning of the QDs grown by metalorganic vapor-phase epitaxy (MOVPE) over the 1.55-μm region at room temperature (RT) is achieved using ultrathin GaAs interlayers underneath the QDs, which suppress As/P exchange to reduce the QD height in a controlled way. Unpolarized photoluminescence from the cleaved side, important for realization of polarization-insensitive semiconductor optical amplifiers, is obtained for closely stacked QDs due to vertical electronic coupling. The wavelength shift due to group-V-atom intermixing in the QDs during growth at higher temperatures of device structures is compensated by adjusting the GaAs interlayer thickness and V/III flow ratio during QD growth. Device quality of the QDs is highlighted by continuous-wave ground-state lasing at RT of narrow ridge-waveguide QD lasers.

A tunable laser for single line gas spectroscopy is realized as a monolithic photonic integrated circuit in an InP based generic foundry platform. The laser operates at wavelengths around 2.0 μm and has a tuning range of 22 nm.

In this letter, we demonstrate electrically pumped continuous-wave lasing at room temperature in microring lasers, which employ a quantum-dot gain medium. Lasing occurs in the important 1.55-mum telecom wavelength range. The 2-mum-wide ring waveguides are made from InGaAsP-InP (100) material suitable for active-passive photonic integrated circuits. Lasing in rings down to 22 mum in diameter is found, with a threshold current of 12.5 mA.

The authors report lasing of InAs/InGaAsP/InP (100) quantum dots (QDs) wavelength tuned into the 1.55 µm telecom region. Wavelength control of the InAs QDs in an InGaAsP/InP waveguide is based on the suppression of As/P exchange through ultrathin GaAs interlayers. The narrow ridge-waveguide QD lasers operate in continuous wave mode at room temperature on the QD ground state transition. The low threshold current density of 580 A/cm2 and low transparency current density of 6 A/cm2 per QD layer, measured in pulsed mode, are accompanied by low loss and high gain with an 80-nm-wide gain spectrum.

Modal gain characterization of mid-infrared semiconductor optical amplifiers intended for an active-passive integration platform is presented. Measured gain profiles reveal the peak values at around 2.07μm and 3dB bandwidth up to 27nm.

We demonstrate all-optical switching in quantum dots (QDs). The switching is studied in an integrated optical combiner circuit. This is a Mach–Zehnder interferometer with an unequal power distribution over the branches. The refractive index is intensity dependent in the branches due to the QDs. Large all-optical nonlinearities are measured. This device is aimed to avoid an unwanted 3-dB loss, fundamental in passive optical splitters.

High-bit-rate nanocavity-based single photon sources in the 1,550-nm telecom band are challenges facing the development of fibre-based long-haul quantum communication networks. Here we report a very fast single photon source in the 1,550-nm telecom band, which is achieved by a large Purcell enhancement that results from the coupling of a single InAs quantum dot and an InP photonic crystal nanocavity. At a resonance, the spontaneous emission rate was enhanced by a factor of 5 resulting a record fast emission lifetime of 0.2 ns at 1,550 nm. We also demonstrate that this emission exhibits an enhanced anti-bunching dip. This is the first realization of nanocavity-enhanced single photon emitters in the 1,550-nm telecom band. This coupled quantum dot cavity system in the telecom band thus provides a bright high-bit-rate non-classical single photon source that offers appealing novel opportunities for the development of a long-haul quantum telecommunication system via optical fibres., 16 pages, 4 figures

We reported the record CW performance of an electrical injection metallic subwavelength-cavity laser with linewidth down to 0.54 nm at room temperature. The instrument-limited linewidth is about one eighth of our previously reported value.

We report lasing in subwavelength cylindrical metallic cavity with 700nm radius at room temperature under pulse current injection. This is the first report of room temperature subwavelength cylindrical metallic cavity laser with electric injection.

We report a fast and Purcell-enhanced single photon source at 1.55 m from a biexciton of a single quantum dot coupled with a photonic crystal nanocavity. Purcell enhancement of five times is demonstrated.

We have demonstrated optical control of quality-factor (Q-factor) using coupled photonic crystal cavities. A double heterostructure (DHS) cavity has been thermo-optically brought in resonance to an adjacent Febry-Perot cavity to reduce the optical confinement and hence decrease the Q-factor. Both the strong and weak coupling phenomena between two cavities have been studied. Up to 50% Q-factor change has been experimentally observed. The corresponding modification of the local density of states enables the control of the spontaneous emission rate of the quantum emitters in the DHS cavity.

We demonstrated room temperature CW operation in a sub-wavelength metallic-cavity laser under electric injection with record performance. The lasing linewidth down to 0.5 nm is about one eighth of the previously reported value.

A tunable laser operating from 2015 – 2040 nm realized as a monolithic InP photonic integrated circuit is presented. The laser uses an intracavity tuning mechanism based on parallel asymmetric Mach-Zehnder interferometers with electro-refractive modulators. The device is intended for a single line gas spectroscopy and was designed and fabricated using a generic integration technology platform.

We report the first room temperature, continuous wave operation of the electrical injection nanolasers with subwavelength cavity. The lasing mode is confined in an InP/InGaAs-SiN-Silver cavity of rectangular cross section operating at 1.55 μm.

We report on high temperature (240K) CW operation of a metal-semiconductor nanolaser under electrical injection. The nanolaser confines light within subwavelength scale in one direction with a physical volume smaller than one wavelength cubic.

We report a novel approach to tuning photonic crystal cavities based on the electrostatic actuation of coupled InGaAsP membranes and we report up to 7 nm mode shift with 8.6 V bias.

We present a method for tuning the resonant wavelength of photonic crystal cavities (PCCs) around 1.55 um. Large tuning of the PCC mode is enabled by electromechanically controlling the separation between two parallel InGaAsP membranes. A fabrication method to avoid sticking between the membranes is discussed. Reversible red/blue shifting of the symmetric/anti-symmetric modes has been observed, which provides clear evidence of the electromechanical tuning, and a maximum shift of 10 nm with < 6 V applied bias has been obtained., 9 pages, 3 figures

We report the formation of site-controlled InAs quantum dots (QDs) on InP pyramids and their integration into planar structures by metalorganic vapor-phase epitaxy. The QD number is reduced by the shrinking pyramid size during growth. Finally the emission from a single QD is observed at 1.55 µm, after optimization of the growth parameters. Employing regrowth epitaxy, position-controlled InAs QDs are integrated into planar InP structures. A smooth surface morphology is obtained at 640 °C during regrowth.

We developed an InP-based photodetector which was bonded on a CMOS wafer containing a Si 3 N 4 -wiring photonic circuit. The detector fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic IC processing. Integration technology and experimental results are presented in this paper.

We present the design, fabrication, and characterization of a membrane coupler processed on an indium phosphide membrane layer on a silicon-on-insulator wafer, that is used for applications in optical interconnects on silicon. Measured coupler efficiency is 50%. The photonic device fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic integrated circuit processing.

We present the design, fabrication and characterization of an InP-based membrane photodetector on an SOI wafer containing a Si-wiring photonic circuit. Measured detector responsivity and 3 dB bandwidth are 0.45 A/W and 33 GHz, respectively. The photonic device fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic IC processing.

We have studied the size dependence of the exciton g-factor in self-assembled InAs/InP quantum dots. Photoluminescence measurements on a large ensemble of these dots indicate a multimodal height distribution. Cross-sectional Scanning Tunneling Microscopy measurements have been performed and support the interpretation of the macro photoluminescence spectra. More than 160 individual quantum dots have systematically been investigated by analyzing single dot magneto-luminescence between 1200nm and 1600 nm. We demonstrate a strong dependence of the exciton g-factor on the height and diameter of the quantum dots, which eventually gives rise to a sign change of the g-factor. The observed correlation between exciton g-factor and the size of the dots is in good agreement with calculations. Moreover, we find a size dependent anisotropy splitting of the exciton emission in zero magnetic field., 15 pages, 7 figures

We have designed, fabricated and characterized an InP-based membrane photodetector on an SOI wafer containing a Si-wiring photonic circuit. New results on RF characterization up to 20 GHz are presented. The detector fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic IC processing.

We present the design, fabrication and a characterization of an InP-based membrane photodetector on an SOI wafer containing a Si-wiring photonic circuit. Waveguide losses in the Si-wiring circuit are below 5 dB/cm. Measured detector responsivity is 0.45 A/W. The photonic device fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic IC processing.

We report the first time ever fabrication and characterisation of a Cross Waveguide Grating (XWG) device.

This article reviews the recent progress in the growth and device applications of InAs/InP quantum dots (QDs) for telecom applications. Wavelength tuning of the metalorganic vapor-phase epitaxy grown single layer and stacked InAs QDs embedded in InGaAsP/InP (100) over the [email protected] region at room temperature (RT) is achieved using ultra-thin GaAs interlayers underneath the QDs. The GaAs interlayers, together with reduced growth temperature and V/III ratio, and extended growth interruption suppress As/P exchange to reduce the QD height in a controlled way. Device quality of the QDs is demonstrated by temperature-dependent photoluminescence (PL) measurements, revealing zero-dimensional carrier confinement and defect-free InAs QDs, and is highlighted by continuous-wave ground-state lasing at RT of narrow ridge-waveguide QD lasers, exhibiting a broad gain spectrum. Unpolarized PL from the cleaved side, important for realization of polarization insensitive semiconductor optical amplifiers, is obtained from closely stacked QDs due to vertical electronic coupling.

We have investigated ICP-etching of deep photonic crystal holes in InP using solely Cl2 as supplied etching gas. The influence of process parameters on hole geometry is discussed and optical test results are reported

We report all-optical switching due to state-filling in quantum dots (QDs) within a Mach-Zehnder Interferometric (MZI) switch. The MZI was fabricated using InGaAsP/InP waveguides containing a single layer of InAs/InP QDs. A 1530-1570 nm probe beam is switched by optical excitation of one MZI-arm from the top. By exciting below the InGaAsP bandgap, we prove that the refractive index nonlinearity is only due to the QDs. The switching efficiency is 2 rad/(microW absorbed power). Probe wavelength insensitivity was obtained using a broad distribution of QDs., 12 pages

We demonstrate all-optical switching in quantum dots. The switching is studied in an integrated optical combiner circuit. This Mach-Zehnder interferometric device is aimed to avoid an unwanted 3-dB loss, fundamental in passive optical splitters.

We report all-optical switching due to state-filling in quantum dots (QDs). The switching energy is as low as 6 fJ since state-filling requires only 2 electron-hole pairs per QD. The single layer of InAs/InP QDs is inserted within a InGaAsP/InP waveguide which are processed into a Mach-Zehnder interferometric switch (MZI). A 1530-1570 nm probe beam is switched by optical excitation of one MZI-arm from above. By exciting below the InGaAsP bandgap, we prove that the refractive index nonlinearity is entirely due to state-filling in the QDs.

The lattice constants of tetragonal PbTiO3 grown by organometallic chemical vapor deposition, vary with average crystallite size in the thin film as determined from line broadening in x‐ray diffraction patterns. The a‐ and c‐lattice constants become equal when the average crystallite size decreases to below ∼5 nm. These data agree with the change in lattice constants as a function of average crystallite size found recently for submicron PbTiO3 powder.

Plasmonic nanolasers and spasers continue to attract a great deal of interest from the physics and nanophotonics community, with the experimental observation of lasing as a focus of research. We report the observation of continuous wave lasing in metallic cavities of deep subwavelength sizes under electrical injection, operating at room temperature. The volume of the nanolaser is as small as 0.42\ensuremath{\lambda}${}^{3}$, where \ensuremath{\lambda} $=$ 1.55 \ensuremath{\mu}m is the lasing wavelength. This demonstration will help answer the question of how small a nanolaser can be made, and will likely stimulate a wide range of fundamental studies in basic laser physics and quantum optics on truly subwavelength scales. In addition, such nanolasers may lead to many potential applications, such as on-chip integrated photonic systems for communication, computing, and detection.

Position and distribution control of 1.55-μm InAs quantum dots (QDs) on truncated InP pyramids grown by selective area Metal Organic Vapor Phase Epitaxy (MOVPE) is reported. The arrangement of the {103}, {115}, and (100) facets on the pyramid top surface is governed by the shape of the pyramid base and top surface area. This allows the precise position and distribution control of the QDs due to preferential nucleation on the {103} and {115} facets. With shrinking QD number upon reduced top surface area, sharp emission from single QDs is observed at 1.55 μm. Regrowth of a passive InP structure around the pyramids establishes submicrometer-scale active-passive integration for efficient microcavity QD nanolasers and single photon sources operating in the 1.55-μm telecom wavelength region and their implementation in photonic integrated circuits.