Silver nanodots and nanoripples have been grown on nanocavity-patterned polycrystalline Au templates by controlled electrodeposition. The initial step is the growth of a first continuous Ag monolayer followed by preferential deposition at nanocavities. The Ag-coated nanocavities act as preferred sites for instantaneous nucleation and growth of the three-dimensional metallic centres. By controlling the amount of deposited Ag, dots of ∼50 nm average size and ∼4 nm average height can be grown with spatial and size distributions dictated by the template. The dots are in a metastable state. Further Ag deposition drives the dot surface structure to nanoripple formation. Results show that electrodeposition on nanopatterned electrodes can be used to prepare a high density of nanostructures with a narrow size distribution and spatial order.

PROCEEDINGS LETTERS 1767shown when the 1 A bias current is applied. Above the threshold, the delay time is negligibly small141. When the regions I, 11, 111, and IV are optically pumped by the increased bias current, the small input currents A andB can exceed the threshold easily and optical outputs with quick response can be obtained. This device was designed from the relation between the cavity length, the threshold current density, and the lasing wavelength. The propagation delay of the half adder is the time required for the transition of the lasing modes. A delay time less than 0.4 ns was achieved"]. Using this functional device we were able to constract an ultra-high-speed optoelectronic adder circuit. CW operation of the dual laser at 18°K was observed[61. CW operation was also acheved with the injection laser half adder.

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We propose a novel lock-in-like light-detection scheme that uses a sinusoidal modulation technique of bias voltages applied to two dynodes in a photomultiplier tube (PMT). By superimposing the sinusoidal modulation signal with a frequency f on the normal bias voltage for one of the dynodes in the PMT, we can obtain a 2f -frequency component from the output of the PMT for a dc (direct current)-level incident light. This is because the gain of the PMT is also modulated with the frequency 2f . By simultaneous modulation of two dynodes separately in the PMT, therefore, we can obtain a 4f -frequency component. This fact means that we are able to detect 4f -frequency-modulated incident light by using the f -frequency dynode-modulation signal, thanks to the multiplier characteristics of the gain of the PMT. In this situation, by setting the value of the load resistor of the PMT large, we can detect the 4f -frequency signal as a dc voltage with a high signal-to-noise ratio. If we vary the phase of the modulation signal for the dynodes over that of the incident one, we can obtain the phase of the incident signal light. In such a sense, we call the scheme a pseudo-lock-in light-detection system, which enables us to construct the system extremely simply. Experimental results for measuring the fluorescence lifetimes of YAG materials and a fluorescence glass are demonstrated followed by the basic performance test of the scheme.