Brian Corbett

73.7 Tb/s (96 x 3 x 256-Gb/s) mode-division-multiplexed DP-16QAM transmission with inline MM-EDFA

Transmission of a 73.7 Tb/s (96 x 3 x 256-Gb/s) DP-16QAM mode-division-multiplexed signal over 119 km of few-mode fiber transmission line incorporating an inline multi mode EDFA and a phase plate based mode (de-)multiplexer is demonstrated. Data-aided 6 x 6 MIMO digital signal processing was used to demodulate the signal. The total demonstrated net capacity, taking into account 20% of FEC-overhead and 7.5% additional overhead (Ethernet and training sequences), is 57.6 Tb/s, corresponding to a spectral efficiency of 12 bits/s/Hz.

Emerging optofluidic technologies for point-of-care genetic analysis systems: a review

This review describes recently emerging optical and microfluidic technologies suitable for point-of-care genetic analysis systems. Such systems must rapidly detect hundreds of mutations from biological samples with low DNA concentration. We review optical technologies delivering multiplex sensitivity and compatible with lab-on-chip integration for both tagged and non-tagged optical detection, identifying significant source and detector technology emerging from telecommunications technology. We highlight the potential for improved hybridization efficiency through careful microfluidic design and outline some novel enhancement approaches using target molecule confinement. Optimization of fluidic parameters such as flow rate, channel height and time facilitates enhanced hybridization efficiency and consequently detection performance as compared with conventional assay formats (e.g. microwell plates). We highlight lab-on-chip implementations with integrated microfluidic control for “sample-to-answer” systems where molecular biology protocols to realize detection of target DNA sequences from whole blood are required. We also review relevant technology approaches to optofluidic integration, and highlight the issue of biomolecule compatibility. Key areas in the development of an integrated optofluidic system for DNA hybridization are optical/fluidic integration and the impact on biomolecules immobilized within the system. A wide range of technology platforms have been advanced for detection, quantification and other forms of characterization of a range of biomolecules (e.g. RNA, DNA, protein and whole cell). Owing to the very different requirements for sample preparation, manipulation and detection of the different types of biomolecules, this review is focused primarily on DNA–DNA interactions in the context of point-of-care analysis systems.

Analysis of Slot Characteristics in Slotted Single-Mode Semiconductor Lasers Using the 2-D Scattering Matrix Method

We use the two-dimensional (2-D) scattering matrix method (SMM) to analyze the slot characteristics in slotted single-mode semiconductor lasers and compare the results with those calculated by the one-dimensional transfer matrix method (TMM). The analysis shows that the 2-D SMM is required to accurately account for the measured results. Using the 2-D SMM simulation, we find that there is almost no reflection at the interface from slot to waveguide while a large reflection exists at the interface from waveguide to slot, and the power loss is much larger than the power reflected. For a single slot, the slot width has little influence on the slot reflectivity, which coincides with the measured results. The reflection and transmission of the slot are found to be exponentially dependent on the slot depth

Discretely Tunable Semiconductor Lasers Suitable for Photonic Integration

A sequence of partially reflective slots etched into an active ridge waveguide of a 1.5 mum laser structure is found to provide sufficient reflection for lasing. Mirrors based on these reflectors have strong spectral dependence. Two such active mirrors together with an active central section are combined in a Vernier configuration to demonstrate a tunable laser exhibiting 11 discrete modes over a 30 nm tuning range with mode spacing around 400 GHz and side-mode suppression ratio larger than 30 dB. The individual modes can be continuously tuned by up to 1.1 nm by carrier injection and by over 2 nm using thermal effects. These mirrors are suitable as a platform for integration of other optical functions with the laser. This is demonstrated by monolithically integrating a semiconductor optical amplifier with the laser resulting in a maximum channel power of 14.2 dBm from the discrete modes.

A Novel Two-Section Tunable Discrete Mode Fabry-PÉrot Laser Exhibiting Nanosecond Wavelength Switching

A novel widely tunable laser diode is proposed and demonstrated. Mode selection occurs by etching perturbing slots into the laser ridge. A two-section device is realized with different slot patterns in each section allowing Vernier tuning. The laser operates at 1.3 mum and achieves a maximum output power of 10 mW. A discontinuous tuning range of 30 nm was achieved with a side mode suppression greater than 30 dB. Wavelength switching times of approximately 1.5 ns between a number of wavelength channels separated by 7 nm have been demonstrated.

Characterization of Ge-on-Si virtual substrates and single junction GaAs solar cells

A virtual substrate consisting of a Ge layer grown directly on Si without an intervening SiGe graded layer is characterized. The nominally 100% Ge overlayer is fully relaxed and contains a small amount (3%) of unintentional Si. A dislocation density of 108 cm−2 is estimated for the virtual substrate prior to GaAs epitaxial growth, which is reduced by a factor of 100 after the growth of GaAs. On this novel virtual substrate 1 cm2 single-junction GaAs photovoltaic cells were realized with an efficiency of 11.7% under AM0 compared with 20.2% for cells grown on a crystalline Ge substrate. Due to the high dislocation density a 50-fold higher dark current is measured in the virtual substrate cells compared to the crystalline Ge cells, leading to a lower short circuit current and open-circuit voltage of the cells fabricated on the virtual substrates. The post-GaAs growth dislocation density is estimated as 1 × 107 cm−2 in the base region and 4 × 105 cm−2 in the emitter region based on modelling and measurements.

Resonant cavity light emitting diode and detector using epitaxial liftoff

Epitaxial liftoff (ELO) is used in a novel manner to form arrays of vertical resonant cavity light emitting diodes (RCLEDs) using two metal mirrors. The epitaxial layers consist of an InP/InGaAs p-i-n structure. Electroluminescence from the vertically emitting resonant cavity is measured CW at room temperature to have a spectral width of 9 meV in contrast to a photoluminescence spectral width of 51 meV for the unprocessed layers. The structure behaves as a resonant detector under reverse bias. Cavities formed in this manner will find wide application in surface emitting and detecting arrays and spatial light modulators, and as a means of studying the physics of spontaneous emission.<<ETX>>

Carrier distribution in InGaN/GaN tricolor multiple quantum well light emitting diodes

Carrier transport in InGaN light emitting diodes has been studied by comparing the electroluminescence (EL) from a set of triple quantum well structures with different indium content in each well, leading to multicolor emission. Both the sequence and width of the quantum wells have been varied. Comparison of the EL spectra reveals the current dependent carrier transport between the quantum wells, with a net carrier flow toward the deepest quantum well.

20 × 960-Gb/s Space-division-multiplexed 32QAM transmission over 60 km few-mode fiber

We show transmission of 20 wavelength-division-multiplexed (WDM) × 960-Gb/s space-division-multiplexed 32QAM modulated channels (spectral efficiency (SE) of 15 bits/s/Hz) over 60 km of few-mode fiber (FMF) with inline few-mode EDFA (FM-EDFA). Soft-decision FEC was implemented and used to achieve error-free transmission.

Practical Design of Lensed Fibers for Semiconductor Laser Packaging Using Laser Welding Technique

We propose a set of guidelines for the practical design of lensed fiber for the optical coupling of semiconductor lasers in butterfly packages using laser welding. These guidelines have optimized the tradeoff between coupling efficiency and alignment tolerance. Moreover, a radius of curvature of 11 mum is shown to be optimal for semiconductor lasers whose divergence angles range from 5deg to 30deg. To experimentally evaluate the design, lensed fibers were assembled by a Nd:YAG laser welding technique in conventional butterfly packages and their coupling efficiencies were 28%-72% without horizontal misalignment compensation.