15,148 research outputs found
Low-power, 10-Gbps 1.5-Vpp differential CMOS driver for a silicon electro-optic ring modulator
We present a novel driver circuit enabling electro-optic modulation with high extinction ratio from a co-designed silicon ring modulator. The driver circuit provides an asymmetric differential output at 10Gbps with a voltage swing up to 1.5V(pp) from a single 1.0V supply, maximizing the resonance-wavelength shift of depletion-type ring modulators while avoiding carrier injection. A test chip containing 4 reconfigurable driver circuits was fabricated in 40nm CMOS technology. The measured energy consumption for driving a 100fF capacitive load at 10Gbps was as low as 125fJ/bit and 220fJ/bit at 1V(pp) and 1.5V(pp) respectively. After flip-chip integration with ring modulators on a silicon-photonics chip, the power consumption was measured to be 210fJ/bit and 350fJ/bit respectively
An ultra fast optical header replacement technology and its application for broadband optical packet switch.
An optical header replacement technology based on Self Electro-optic Effect Devices (SEEDs) is presented. By using the measurement result of a 75 ÎĽm long SEED device, we simulate an 8 Gbps throughput is achievable. Based on the switching characteristics of SEEDs, we proposed several methods to improve the SEEDs switching speed. An ultra fast switching speed at 50 Gbps is achievable by integrating external components and applying a pair of preset pulses. Due to the convenience of operation in both the optical domain and the electrical domain, it is very suitable for optical header processing; therefore it is an ideal candidate solution for optical fast packet switch
Digital canopus tracker digital electronics
Circuitry has been developed for digital control of the Canopus tracker. A feasibility and demonstration breadboard has been constructed using microelectronic integrated circuits. The breadboard contains the digital circuits necessary for closed-digital logic necessary for star acquisition, particle rejection, programmable gate selection, cone angle selection, and routing of the digital roll error signal
Increasing efficiency of a linear-optical quantum gate using an electronic feed forward
We have successfully used a fast electronic feed forward to increase the
success probability of a linear optical implementation of a programmable phase
gate from 25% to its theoretical limit of 50%. The feed forward applies a
conditional unitary operation which changes the incorrect output states of the
data qubit to the correct ones. The gate itself rotates an arbitrary quantum
state of the data qubit around the z-axis of the Bloch sphere with the angle of
rotation being fully determined by the state of the program qubit. The gate
implementation is based on fiber optics components. Qubits are encoded into
spatial modes of single photons. The signal from the feed-forward detector is
led directly to a phase modulator using only a passive voltage divider. We have
verified the increase of the success probability and characterized the gate
operation by means of quantum process tomography. We have demonstrated that the
use of the feed forward does not affect either the process fidelity or the
output-state fidelities
Optical computing by injection-locked lasers
A programmable optical computer has remained an elusive concept. To construct
a practical computing primitive equivalent to an electronic Boolean logic, one
should find a nonlinear phenomenon that overcomes weaknesses present in many
optical processing schemes. Ideally, the nonlinearity should provide a
functionally complete set of logic operations, enable ultrafast all-optical
programmability, and allow cascaded operations without a change in the
operating wavelength or in the signal encoding format. Here we demonstrate a
programmable logic gate using an injection-locked Vertical-Cavity
Surface-Emitting Laser (VCSEL). The gate program is switched between the AND
and the OR operations at the rate of 1 GHz with Bit Error Ratio (BER) of 10e-6
without changes in the wavelength or in the signal encoding format. The scheme
is based on nonlinearity of normalization operations, which can be used to
construct any continuous complex function or operation, Boolean or otherwise.Comment: 47 pages, 7 figures in total, 2 tables. Intended for submission to
Nature Physics within the next two week
The Los Alamos Trapped Ion Quantum Computer Experiment
The development and theory of an experiment to investigate quantum
computation with trapped calcium ions is described. The ion trap, laser and ion
requirements are determined, and the parameters required for quantum logic
operations as well as simple quantum factoring are described.Comment: 41 pages, 16 figures, submitted to Fortschritte der Physi
EMCCDs for space applications
This paper describes a qualification programme for Electron-Multiplication Charge Coupled Devices (EMCCDs) for use in space applications. While the presented results are generally applicable, the programme was carried out in the context of CCD development for the Radial Velocity Spectrometer (RVS) instrument on the European Space Agency's cornerstone Gaia mission. We discuss the issues of device radiation tolerance, charge transfer efficiency at low signal levels and life time effects on the electron-multiplication gain. The development of EMCCD technology to allow operation at longer wavelengths using high resistivity silicon, and the cryogenic characterisation of EMCCDs are also described
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