Abstract: A method for dynamic characterization of an electrochemical system (such as a lithium-ion battery) is provided, comprising exciting an electrochemical system with a plurality of double-pulse sequences, each comprising a constant-current discharge pulse, a constant-current charge pulse having the same pulse width and pulse amplitude, and a zero-current period between the pulses; and calculating an impulse response, using a recursive or matrix-based method, to dynamically characterize the electrochemical system. A constant state-of-charge is maintained in the electrochemical system. Therefore the signal-to-noise ratio is high due to the repetition of the driving sequence. This method may be employed for on-line determination of the impedance spectrum of an electrochemical system, since the cycling profile can be easily integrated into charge/discharge profiles. Batteries (and other devices) can be diagnosed at high speed and with high accuracy. The double-pulse sequence is robust for fairly noisy systems.

Abstract: A method for monitoring a lithium-ion battery cell includes monitoring a battery cell voltage and a corresponding charge capacity of the battery cell during an electric power event which may include either an electric power charge event or an electric power discharge event. A measured charge-capacity-derivative is determined by differentiating the charge capacity in relation to the corresponding battery cell voltage during the electric power event. The measured charge-capacity-derivative is compared with a preferred anode charge-capacity-derivative of an anode charge curve (for electric power discharge events) or an anode discharge curve (for electric power charge events), and with a preferred cathode charge-capacity-derivative of a cathode charge curve (for electric power charge events) or a cathode discharge charge curve (for electric power discharge events).

Abstract: A method for monitoring a lithium-ion battery cell includes monitoring a battery cell voltage and a corresponding state of charge of the battery cell during an electric power event which may include either an electric power charge event or an electric power discharge event. A measured potential-derivative is determined by differentiating the battery cell voltage in relation to the corresponding state of charge of the battery during the electric power event. The measured potential-derivative is compared with a preferred anode potential-derivative of an anode charge curve (for electric power discharge events) or an anode discharge curve (for electric power charge events), and with a preferred cathode potential-derivative of a cathode charge curve (for electric power charge events) or a cathode discharge charge curve (for electric power discharge events).

Abstract: Presented is a method and system for phase locking a multi-stage parallel fiber amplifier. The method comprises receiving a signal beam from a first stage, in one path of the multi-stage fiber amplifier, onto a fiber that is pumped to produce a saturated signal beam that is then output to a second stage that outputs an amplified beam. A characteristic of the of the saturated signal beam is that its phase and amplitude do not substantially change based on the amplitude of the signal beam input onto the fiber. The method further detects a portion of the amplified beam to produce a phase indication of the amplified beam relative to amplified beams of the other paths of the multi-stage fiber amplifier. The method modulates the pump level of the first stage to control the phase of amplified beam, and further controls the phases of the other amplified beams of the other paths to phase lock the multi-stage parallel amplifier.

Abstract: A method for monitoring a lithium-ion battery cell includes monitoring a battery cell voltage and a corresponding charge capacity of the battery cell during an electric power event which may include either an electric power charge event or an electric power discharge event. A measured charge-capacity-derivative is determined by differentiating the charge capacity in relation to the corresponding battery cell voltage during the electric power event. The measured charge-capacity-derivative is compared with a preferred anode charge-capacity-derivative of an anode charge curve (for electric power discharge events) or an anode discharge curve (for electric power charge events), and with a preferred cathode charge-capacity-derivative of a cathode charge curve (for electric power charge events) or a cathode discharge charge curve (for electric power discharge events).

Abstract: A method for monitoring a lithium-ion battery cell includes monitoring a battery cell voltage and a corresponding state of charge of the battery cell during an electric power event which may include either an electric power charge event or an electric power discharge event. A measured potential-derivative is determined by differentiating the battery cell voltage in relation to the corresponding state of charge of the battery during the electric power event. The measured potential-derivative is compared with a preferred anode potential-derivative of an anode charge curve (for electric power discharge events) or an anode discharge curve (for electric power charge events), and with a preferred cathode potential-derivative of a cathode charge curve (for electric power charge events) or a cathode discharge charge curve (for electric power discharge events).

Abstract: A method of determining and predicting a state of a rechargeable battery device in real time involves measuring a current and a voltage of the rechargeable battery in real time, inputting the measured current and voltage into an algorithm, and applying the algorithm to determine the state of the rechargeable battery. The algorithm includes a first mathematical model based on a direct solution of at least one differential equation characterizing an equivalent RC circuit of the battery as a function of time. The first model generates a plurality of parameters that are usable to determine the state of the battery. The algorithm further includes a second mathematical model configured to regress the parameters over time, and a third mathematical model configured to estimate the state of the battery.

Abstract: In one of the embodiments, a dark channel array is provided which includes gain channels, each configured to emit an output beam from an output surface and to have a light wave propagating therethrough. It further includes a dark channel configured to emit an output beam from the output surface of the dark channel array and to have a light wave propagating in the dark channel, such that output beams from the plurality of gain channels are coherently coupled in phase with each other. The dark channel array is configured such that the dark channel captures a portion of the output beam from at least two of the plurality of gain channels by radiant coupling.

Abstract: Method and system for transmitting optical clock signals and quantum key signals on a single optical channel. A multi-photon optical clock signal is received at an electro-optic switch at a first clock rate. The electro-optic switch may be configured for an interval defined by a second clock rate for generating a single photon quantum key signal. The multi-photon optical clock signal and the single photon quantum key signal are combined such that the single optical channel transmits the single photon quantum key signal at a first interval and the multi-photon optical clock signal at a second interval. The quantum key signal is transmitted from a transmitter at a first timing, and detected by a detector at a receiver. An output signal of the detector is sampled at a second timing that is delayed relative to the first timing for reducing quantum bit error rate.

Abstract: An optical coupler is provided for a passive coherent combination of fiber lasers/amplifiers. A plurality of optical fibers are arranged in a close-packed hexagonal array having 1+3n(n+1) fibers with (3/2)(n2?n)+3 interferometrically dark fibers and (3/2)(n2+3n)?2 light fibers, where n is an integer greater than or equal to 1. Each optical fiber has a first end and a second end. The plurality of optical fibers are fused together along a section of each optical fiber proximate the first end of each optical fiber to form a fused section having a fiber axis. The fused section of the plurality of optical fibers is tapered to form a tapered region. A facet is at an end of the fused section. The facet is disposed in a direction perpendicular to the fiber axis. The coherent pattern is highly stable against perturbation.

Abstract: In one embodiment, a dark channel array is provided which includes gain channels, each gain channel being configured to emit an output beam, and which includes a dark channel configured to cause output beams from the gain channels to be coherently couple in phase with each other.

Abstract: A method and system for transmitting optical clock signals and quantum key signals on a single optical channel, and for reducing quantum bit error rate in a quantum key distribution system. The method includes receiving a multi-photon optical clock signal at an electro-optic switch at a first clock rate. The electro-optic switch may be configured for an interval defined by a second clock rate for generating a single photon quantum key signal. The multi-photon optical clock signal and the single photon quantum key signal may be combined such that the single optical channel transmits the single photon quantum key signal at a first interval and the multi-photon optical clock signal at a second interval. The quantum key signal may be transmitted from a transmitter at a first timing, and detected by a detector at a receiver. An output signal of the detector may be sampled at a second timing that is delayed relative to the first timing for reducing quantum bit error rate.

Abstract: A multiple-fiber, stretched, fused and cleaved coupler designed to act as an output window to a fiber laser array or fiber-coupled laser array, in which the stretch, length and/or position of the fibers is chosen facilitate the in-phase oscillation of the lasers in the array. The in-phase oscillation of the lasers is facilitated by making one or more of the fibers interferometrically dark and having a different propagation constant than the other fibers. The other fibers, the interferometrically lit ones, are made to have fairly uniform intensity under the same collimated illumination.