Instead of the fixed pulse durations in conventional differential normal pulse voltammetry, a PC-based instrument using adaptable pulse duration vectors for background current correction has been proposed and implemented. With this PC-based instrument, a sequence of pulse duration vectors is determined in an initial blank solution voltammetry by assigning a decay percentage constant to the charging current. These vectors are then used in the subsequent test solution in order to obtain a pure oxidation current response in a resulting voltammogram with its corresponding features. Experimental results are presented to show the effectiveness and advantages of the PC-based instrument for the measurements of dopamine in a phosphate buffered solution.
Two muhually delay-coupled semiconductor lasers operating at period-one dynamics, which behave like an optically injected laser with optical feedback, are studied for microwave generation. Microwaves with a hmable frequency and narrow linewidth are generated.
This study investigates an optically injected semiconductor laser operating at period-one nonlinear dynamics for all-optical microwave generation. A novel, to the best of our knowledge, all-optical stabilization scheme is proposed to greatly enhance the spectral purity of such generated microwaves, which sends a small fraction of the injected laser output back to the injecting laser, not the injected laser itself. Mutual injection with highly different injection power between the two lasers, i.e., highly asymmetric mutual injection, is thus formed. As a result, the microwave linewidth is reduced by up to at least 85 times, the phase noise variance is improved by up to at least 750 times, and a side-peak suppression ratio of more than 44 dB is achieved. Microwave generation that is tunable up to at least 110 GHz with a 3-dB linewidth down to below 2 kHz is realized.
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