In this article, we report on long wavelength (1.27 μm) single-mode micro-structured photonic crystal strained InGaAs
quantum wells VCSELs for optical interconnection applications. Single fundamental mode room-temperature
continuous-wave lasing operation was demonstrated for devices designed and processed with different two-dimensional
etched patterns. The conventional epitaxial structure was grown by Metal-Organic Vapor Phase Epitaxy (MOVPE) and
contains fully doped GaAs/AlGaAs DBRs, one oxidation layer and three strained InGaAs quantum wells. The holes were
etched half-way through the top-mirror following various designs (triangular and square lattices) and with varying hole's
diameters and pitches.
We obtained up to 1.7 mW optical output power and more than 30 dB Side-Mode Suppression Ratio (SMSR) at
room temperature and in continuous wave operation. Systematic static electrical, optical and spectral characterization
was performed on wafer using an automated probe station. Numerical modeling using the MIT Photonic-Bands (MPB
) package of the transverse modal behaviors in the photonic crystal was performed using the plane wave method in
order to understand the index-guiding effects of the chosen patterns, and to further optimize the design structures for
mode selection at the given wavelength.
In this article, we present our results on long wavelength (1.1 μm) single-mode micro-structured photonic crystal
strained InGaAs quantum wells VCSELs for optical interconnection applications. Single fundamental mode roomtemperature
continuous-wave lasing operation was demonstrated for devices designed and processed with a number of
different two-dimensional etched patterns. The conventional epitaxial structure was grown by Molecular Beam Epitaxy
(MBE) and contains fully doped GaAs/AlGaAs DBRs, one oxidation layer and three strained InGaAs quantum wells.
The holes were etched half-way through the top-mirror following various designs (triangular and square lattices) and
with varying hole's diameters and pitches.
At room temperature and in continuous wave operation, micro-structured 50 µm diameter mesa VCSELs with
10 μm oxidation aperture exhibited more than 1 mW optical power, 2 to 5 mA threshold currents and more than 30 dB
side mode suppression ratio at a wavelength of 1090 nm. These structures show slight power reduction but similar
electrical performances than unstructured devices. Systematic static electrical, optical and spectral characterization was
performed on wafer using an automated probe station. Numerical modeling using the MIT Photonic-Bands (MPB )
package of the transverse modal behaviors in the photonic crystal was performed using the plane wave method in order
to understand the index-guiding effects of the chosen patterns, and to further optimize the design structures for mode
selection at extended wavelength range.
In this article, we report our results on 1.3&mgr;m VCSELs for optical interconnection applications. Room
temperature continuous-wave lasing operation is demonstrated for top emitting oxide-confined devices with three
different active materials, highly strained InGaAs/GaAs(A) and GaInNAs/GaAs (B) multiple quantum wells (MQW) or
InAs/GaAs (C) quantum dots (QD). Conventional epitaxial structures grown respectively by Metal Organic Vapour
Phase Epitaxy (MOVPE), Molecular Beam Epitaxy (MBE) and MBE, contain fully doped GaAs/AlGaAs DBRs. All
three epilayers are processed in the same way. Current and optical confinement are realized by selective wet oxidation.
Circular apertures from 2 (micron)m to 16 (micron)m diameters are defined.
At room temperature and in continuous wave operation, all three systems exhibit lasing operation at
wavelengths above 1 275nm and reached 1 300nm for material (A). Typical threshold currents are in the range [1-
10]mA and are strongly dependent firstly on oxide diameter and secondly on temperature. Room temperature cw
maximum output power corresponds respectively to 1.77mW, 0.5mW and 0.6mW. By increasing driving current,
multimode operation occurs at different level depending on the oxide diameter. In case (A), non conventional modal
behaviors will be presented and explained by the presence of specific oxide modes.
Thermal behaviors of the different devices have been compared. In case (A) and (C) we obtain a negative T0.
We will conclude on the different active materials in terms of performances with respect to 1300nm VCSEL
In the context of optical interconnection applications, we report on results obtained on strained InGaAs quantum well Vertical Cavity Surface Emitting Lasers (VCSELs). Our devices are top p-type DBR oxide-confined VCSEL, grown by metalorganic vapour-phase epitaxy (MOVPE). These lasers exhibit low threshold currents and deliver up to 1.77 mW in continuous wave operation at room temperature. Fundamental mode continuous-wave lasing at wavelengths beyond 1300 nm at room temperature is reached for a 4 μm oxide diameter VCSEL. The particular design of the active layer based on a large detuning between the gain maximum and the cavity resonance gives our devices a very specific thermal and modal behaviour. Therefore, we study the spectral and spatial distributions of the transverse modes by near field scanning optical microscopy using a micropolymer tip at the end of an optical fibre.
We report results on strained InGaAs quantum well Vertical Cavity Surface Emitting Lasers (VCSELs) for optical interconnection applications. The structure was grown by metalorganic vapour-phase epitaxy (MOVPE) and processed as top p-type DBR oxide-confined device. Our VCSELs exhibit low threshold currents and deliver up to 1.77 mW in continuous wave operation at room temperature. Fundamental mode continuous-wave lasing at wavelengths beyond 1300 nm is demonstrated at room temperature. The thermal behaviour of our devices is explained through the threshold current-temperature characteristics. Furthermore, the effective index model is used to understand the modal behaviour.
We present an approach for systematic high-speed characterization of VCSELs and discuss both its potential benefits and problems. We show how the VCSEL dynamics, under certain conditions, can be well described by a small number of key parameters that can be extracted from measurements and used for further optimization. The calibrated small signal modulation responses of the laser are measured and fitted to an analytical transfer function allowing the estimation of the resonance frequency, damping factor and parasitic cut-off at different bias points. From this data the relative importance of different bandwidth limiting effects due to damping, thermal heating and parasitics can be deducted. We illustrate the approach on 850nm datacom VCSELs using either ion implantation, selective oxidation or semi-insulating regrowth for current confinement. The bandwidth ofthe implanted device appears to be limited by parasitics effects to 3.3GHz. Due to a much smaller injection diameter, the oxidized VCSEL reaches 10GHz, being mainly limited by the high damping. Finally the regrown VCSEL operates up to 5GHz, limited by the parasitics
MITEL Semiconductor is developing the next generation low cost, high performance transceivers for data communication. The increasing quantity of data being transferred over the Internet demands very high capacity interconnects. A low cost, high-performance alternative is the use of parallel fiber interconnects where the light is, for example, coupled into a 12channel fiber-ribbon. Parallel interconnects require good uniformity in order to reduce escalating costs and complexity. In this paper we report on the static and the modulation properties of 850nm multimode oxide VCSELs for use in such Gb/s transceiver system. Static power-current-voltage characteristics with good uniformity were obtained for different structures, with threshold currents down to sub-mA. A maximum small signal 3-dB bandwidth of 10 GHz and a modulation current efficiency up to 8.4 GHztsJ[rnA] were measured. Single channel results are presented for VCSELs operated at data rates from 2.5-10Gb/s.
Vertical cavity surface emitting lasers (VCSEL) operating around 850 nm are finding escalating markets in fiber optical communication applications, currently mainly at data rates between 1 and 2,5 Gbit/s. More than 3 million device hours without failures at temperatures up to 100 degrees Celsius proves that the reliability of the VCSEL satisfies the requirements for these applications. Results for oxidized as well as implanted devices are discussed and designs for both common anode and common cathode driving conditions are described. We demonstrate the application of our VCSEL design to arrays with passive alignment for parallel data communication over fiber ribbon. As examples of visible components for communication over plastic optical fiber, results for resonant cavity light emitting diodes will be shown and compared to red VCSELs.
We report on two AlGaInP-based visible VCSEL designs based on different current confinement schemes, ion implantation and selective oxidation, and we compare the respective performances with a particular interest on the modulation properties. The implanted device operated continuous wave (CW) up to 40 degrees Celsius. Threshold current of 7 mA, threshold voltage of 2.5 V and maximum optical power of 0.3 mW were measured at room temperature. The small signal modulation responses were fitted using a 3-poles model, allowing the estimation of various parameters such as resonance frequency, damping factor and parasitic cut-off. The maximum 3dB- bandwidth was shown to be 2.1 GHz, limited both by thermal and parasitic effects. 'Error-free' transmission at 1 Gb/s was demonstrated through 50-meter of graded-index POF. The selectivity oxidized devices achieve much higher output power (1.8 mW for the 10 micrometer opening diameter) with threshold current as low a 1.5 mA and threshold voltage of 2.1 V at room temperature, and operate CW up to 49 degrees Celsius. The maximum 3 dB-bandwidth was 4.5 GHz. Modulation current efficiency factor up to 2.8 GHz/(root)[mA] was measured.