New polarisation-control scheme for optical heterodyne receiver using two Faraday rotators

A new state-of-polarisation (SOP) control scheme using two Faraday rotators is proposed. It features low optical insertion loss and quick response. Experiment shows that the receiver output is stable regardless of drastic SOP changes in the signal.     

Photon-counting receiver in near-infra-red region: use of GaInAs avalanche photodiode

A photon-counting receiver using a GaInAs avalanche photodiode has been constructed. The receiver has a quantum efficiency greater than 1% in the spectral range from 800 to 1600 nm, where no practical photomultipliers are available. The real-time recording of single photon incidence is also achieved with 20 ns time resolution.<>     

A 10 Gb/s optical heterodyne detection experiment using a 23 GHzbandwidth balanced receiver

A balanced receiver for multigigabit-per-second coherent optical transmission systems is described. A balanced optical receiver with a frequency bandwidth of 23 GHz is achieved by connecting an InGaAs twin-p-i-n photodiode to a 0.5-30.0 GHz GaAs monolithic distributed amplifier fabricated with a soldier bump flip-chip interconnection technique. An experiment which demonstrated that this receiver has the potential for use in 10-Gb/s optical CPFSK (continuous-phase frequency shift keying) heterodyne detection systems was conducted     

Physiological role of Ca2+-permeable nonselective cation channel in endothelin-1-induced contraction of rabbit aorta

The alpha-amylase of Streptomyces sp. IMD 2679 was subject to catabolite repression. Four different growth rates were achieved when the organism was grown at 40 degrees C and 55 degrees C in the presence and absence of cobalt, with an inverse relationship between alpha-amylase production and growth rate. Highest alpha-amylase yields (520 units/ml) were obtained at the lowest growth rate (0.062 h-1), at 40 degrees C in the absence of cobalt, while at the highest growth rate (0.35 h-1), at 55 degrees C in the presence of cobalt, alpha-amylase production was decreased to 150 units/ml. As growth rate increased, the rate of specific utilisation of the carbon source maltose also increased, from 46 to 123 micrograms maltose (mg biomass)-1 h-1. The pattern and levels of alpha-glucosidase (the enzyme degrading maltose) detected intracellularly in each case, indicate that growth rate effectively controls the rate of feeding of glucose to the cell, and thus catabolite repression.     

Topology optimization for reduction of vibration caused by magnetic harmonic excitation

We apply the homogenization design method (HDM) to reduce the vibration level of a structure excited by magnetic harmonic force. We do this by obtaining the optimal material distribution of the structure to minimize the frequency response. We first use the Maxwell stress method to compute the magnetic force and then apply HDM for the optimization. Results show that the HDM can be used to minimize the frequency response. This method can also be applied to other rotary electrical devices such as motors and generators.     

Low-noise multiwavelength transmitter using spectrum-slicedsupercontinuum generated from a normal group-velocity dispersion fiber

Aiming at the application of supercontinuum (SC) generated from a fiber with a normal group-velocity dispersion (GVD) to multiwavelength transmitters, we theoretically study the enhancement of optical-amplifier noise in the SC-generation and spectrum-slicing processes. We find that significant enhancement of noise is not observed in these processes. The bit error rate measurement actually shows that the power penalty induced by these processes is less than 1 dB in all spectrum-sliced channels. These results assure low noise of the multiwavelength transmitter using spectrum-sliced SC generated in a normal GVD fiber     

Room temperature continuous wave operation of GaInP/AlInP visible-light laser with GaInP/AlInP superlattice confinement layer grown by gas source molecular beam epitaxy

A remarkable threshold current density reduction (from 3.5 kA/cm/sup 2/ to 1.6 kA/cm/sup 2/) of GaInP/AlInP visible light lasers grown by gas source molecular beam epitaxy (GS-MBE) was obtained by introducing 50 pairs of GaInP(7.1 AA)/AlInP(7.1 AA) short period superlattice confinement (SLC) layers. As a result, the room temperature continuous wave (CW) operation was obtained at 669 nm with a minimum threshold current of 50 mA and maximum light output of 10.5 mW.<>