Papers by Sanguan Anantathanasarn
Opt Express, 2007
For the first time passive mode-locking in two-section quantum-dot lasers operating at wavelength... more For the first time passive mode-locking in two-section quantum-dot lasers operating at wavelengths around 1.55 µm is reported. Pulse generation at 4.6 GHz from a 9-mm long device is verified by background-free autocorrelation, RF-spectra and real-time oscilloscope traces. The output pulses have a 7 nm optical bandwidth and are stretched in time and heavily up-chirped with a value of 20 ps/nm. From a 7 mm long device Q-switching is observed over a large operating regime. The lasers have been realized using a fabrication technology that is compatible with further photonic integration, and can perform the function of e.g. a mode-comb generator.
Applied Surface Science, 2003
ABSTRACT (001)-Oriented GaAs metal–insulator–semiconductor (MIS) structures having a silicon inte... more ABSTRACT (001)-Oriented GaAs metal–insulator–semiconductor (MIS) structures having a silicon interface control layer (Si ICL) were fabricated on surfaces having Ga-rich (4×6) reconstructions. Si ICL was grown by molecular beam epitaxy. MIS structures were fabricated by partially converting Si ICL to SiNx by direct nitridation, and further depositing a thick SiO2 layer on top as the main passivation dielectric by plasma-assisted chemical vapor deposition. Reflection high-energy electron diffraction, in situ X-ray photoelectron spectroscopy and MIS capacitance–voltage (C–V) techniques were used for characterization. The initial surface reconstruction was found to have a surprisingly strong effect on the degree of Fermi level pinning at the MIS interface. In contrast to the standard As-rich (2×4) surface, which results in strongly pinned MIS interfaces, the novel SiO2/SiNx/Si ICL/GaAs MIS structures formed on “genuine” (4×6) surface realized complete unpinning of Fermi level over the entire band gap with a minimum interface state density of 4×1010cm−2eV−1 range.
Review of Scientific Instruments, 2007
Review of Scientific Instruments, 2005
Butt-joint integrated extended cavity InAs/InP (100) quantum dot (QD) Fabry-Pérot laser devices e... more Butt-joint integrated extended cavity InAs/InP (100) quantum dot (QD) Fabry-Pérot laser devices emitting around 1.55 µm are demonstrated. Continuous wave lasing at room temperature is realized with devices of different lengths. The threshold currents, transparency current density, and external differential quantum efficiency are all comparable to those of all-active QD lasers. The Butt-joint reflectivity for straight waveguides is below -
Wavelength tuning of single and vertically stacked InAs quantum dot ͑QD͒ layers embedded in InGaA... more Wavelength tuning of single and vertically stacked InAs quantum dot ͑QD͒ layers embedded in InGaAsP / InP ͑100͒ grown by metal organic vapor-phase epitaxy is achieved by controlling the As/ P surface exchange reaction during InAs deposition. The As/ P exchange reaction is suppressed for decreased QD growth temperature and group V-III flow ratio, reducing the QD size and photoluminescence ͑PL͒ emission wavelength. The As/ P exchange reaction and QD PL wavelength are then reproducibly controlled by the thickness of an ultrathin ͑0-2 ML͒ GaAs interlayer underneath the QDs. Submonolayer GaAs coverages result in a shape transition from QDs to quantum dashes at low group V-III flow ratio. Temperature dependent PL measurements reveal excellent optical properties of the QDs up to room temperature with PL peak wavelengths in the technologically important 1.55 m region for telecom applications. Widely stacked QD layers are reproduced with identical PL emission to increase the active volume, while closely stacked QD layers reveal a systematic PL redshift and linewidth reduction due to vertical electronic coupling which is proven by the linear polarization of the cleaved-side PL changing from in plane to isotropic.
A quantum dot active layer is used in a novel, highly scaleable monolithic optical switch matrix ... more A quantum dot active layer is used in a novel, highly scaleable monolithic optical switch matrix architecture. Electronically paired semiconductor optical amplifiers gates are implemented in a four-input four-output configuration to reduce the electrical connections and control complexity. Low power penalty 10Gb/s routing at a wavelength of 1555nm is demonstrated. Increasingly high-capacity data transfer in storage area networking, high performance computing, and server networks is driving research into increasingly elaborate photonic switched interconnect test-beds [1-4]. The need for low-latency, high capacity, scalable switch fabrics with low driver complexity, excellent crosstalk and the broad gain bandwidth has lead to a particular focus on semiconductor optical amplifier (SOA) based switches. However, considerable integration is required to remove complex packaging-related restrictions such as the high numbers of fibre pigtails, power consuming cooler circuits, and the complex...
2008 International Conference on Photonics in Switching, 2008
Figure 1 : a) Schematic crossbar element, b) Photograph of the fabricated switch matrix.
OFC/NFOEC 2008 - 2008 Conference on Optical Fiber Communication/National Fiber Optic Engineers Conference, 2008
A novel wavelength conversion concept based on InAs/InP(100) quantum-dot ringlaser structure is d... more A novel wavelength conversion concept based on InAs/InP(100) quantum-dot ringlaser structure is demonstrated requiring no external laser, optical inversion or optical filtering. Demonstration at 622Mb/s for a 2mm ring, suggests applicability for much higher speeds
Butt-joint integrated extended cavity InAs/InP (100) quantum dot (QD) Fabry-Pérot laser devices e... more Butt-joint integrated extended cavity InAs/InP (100) quantum dot (QD) Fabry-Pérot laser devices emitting around 1.55 µm are demonstrated. Continuous wave lasing at room temperature is realized with devices of different lengths. The threshold currents, transparency current density, and external differential quantum efficiency are all comparable to those of all-active QD lasers. The Butt-joint reflectivity for straight waveguides is below-40 dB. Light versus current curves and lasing spectra reveal that for low current, lasing starts on the QD ground state transition, while excited state lasing sets in with increasing current.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
Optics Express, 2007
For the first time passive mode-locking in two-section quantum-dot lasers operating at wavelength... more For the first time passive mode-locking in two-section quantum-dot lasers operating at wavelengths around 1.55 µm is reported. Pulse generation at 4.6 GHz from a 9-mm long device is verified by background-free autocorrelation, RF-spectra and real-time oscilloscope traces. The output pulses have a 7 nm optical bandwidth and are stretched in time and heavily up-chirped with a value of 20 ps/nm. From a 7 mm long device Q-switching is observed over a large operating regime. The lasers have been realized using a fabrication technology that is compatible with further photonic integration, and can perform the function of e.g. a mode-comb generator.
2008 10th Anniversary International Conference on Transparent Optical Networks, 2008
In this paper, some of the activities towards the fabrication of Photonic Integrated Circuits at ... more In this paper, some of the activities towards the fabrication of Photonic Integrated Circuits at the COBRA Research Institute are summarized. Firstly, rate equations are used for the understanding of instability and dynamics in multilongitudinal mode semiconductor lasers. Secondly, we report the results of our investigation on broad-bandwidth frequency comb generators based on novel mode-locked InAs/InGaAsP/InP quantum dot laser diodes. In addition, we will show the integration of two-dimensional pillar-based photonic crystal waveguides in an InGaAsP/InP photonic integrated circuit.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2003
ABSTRACT In order to achieve better surface passivation on technologically important (001) GaAs s... more ABSTRACT In order to achieve better surface passivation on technologically important (001) GaAs surfaces, microscopic and macroscopic properties of the clean (001) surface with Ga-rich (4×6) reconstruction, and effects of monolayer level Si deposition on this surface, were investigated. According to scanning tunneling spectroscopy and contactless capacitance–voltage (C–V) measurements, the Ga-rich genuine (G-)(4×6) surface had high-density acceptor-type states above EC-0.5 eV. However, the surface exhibited a much lower and wider surface state density (NSS) distribution as well as a much stronger band-edge photoluminescence (PL) intensity than the conventional As-rich surfaces. Irradiation of Si molecular beam on the (4×6) surface resulted in epitaxial growth of Si. This completely removed the acceptor-type surface states from the energy gap, and further enhanced the PL intensity. The result indicates that the Ga-rich G-(4×6) surface is more ordered and more stable against processing than conventional As-rich surfaces. Metal–insulator–semiconductor capacitors fabricated by further depositing a thick SiO2 layer indicated that the Fermi level was completely unpinned over the entire band gap. © 2003 American Vacuum Society.
Physics and Simulation of Optoelectronic Devices XVI, 2008
In this paper an overview is given of the results we have obtained at the COBRA Research Institut... more In this paper an overview is given of the results we have obtained at the COBRA Research Institute in our work on passively modelocked semiconductor lasers operating in the 1.5 µm wavelength region. Most results concern modelocked ring lasers that are realized monolithically in the InP/InGaAsP materials system as well as simulations using lumped element and traveling wave type models. The experimental results show that the ring lasers appear as the more stable type of lasers. The modeling results show the importance of using a symmetrical configuration in the ring laser for stable operation. Most recent results on linear modelocked quantum dot lasers at 1.5 µm indicate the improvements possible using these materials.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2001
ABSTRACT An attempt was made to passivate the GaAs surface by a Si3N4/c-GaN/GaAs passivation stru... more ABSTRACT An attempt was made to passivate the GaAs surface by a Si3N4/c-GaN/GaAs passivation structure, having an ultrathin cubic GaN as an interface control layer (ICL) with a wide energy gap. The GaN ICL was formed by direct nitridation of GaAs with active nitrogen radical species in a molecular beam epitaxy (MBE) chamber. A detailed in situ x-ray photoelectron spectroscopy study confirmed formation of 1 or 2 monolayers of pseudomorphic cubic GaN layer. A remarkable increase of the quantum efficiency of photoluminescence (PL) by a factor of 30 was obtained by forming the passivation structure on the MBE grown clean (001) GaAs under optimum conditions. This indicates a large reduction of the surface recombination velocity. The increase of the PL intensity was extremely stable, maintaining its value even after leaving the sample in air for 2 months. Detailed ultrahigh vacuum contactless capacitance–voltage (C–V) measurements and usual metal–insulator–semiconductor C–V measurement indicated reduction of interface states, realizing a wide movement of the Fermi level within the midgap region. © 2001 American Vacuum Society.
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Papers by Sanguan Anantathanasarn