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A novel design method of microstrip diplexer without extra matching circuit is proposed in this paper. Because of the synthesizable circuit parameters and controllable transmission zeros (TZs) in composite resonator (CR) cell, diplexer A based on CR cell is proposed. By allocating TZs at center frequency of the opposite channel, as well as the using of impedance transformations of J inverters, high isolation and good passband selectivity are realized in diplexer A without extra matching circuit. In order to improve the stopband performance, diplexer B based on coupled CR cells is proposed. Furthermore, diplexer B using the proposed design method is implemented by directly combining two bandpass filters (BPFs), which simplifies significantly the design process of diplexers. Diplexer A operated at 1/1.2 GHz and diplexer B operated at 1/1.5 GHz are designed and fabricated. The measured isolation characteristics in diplexer A and diplexer B are all higher than 40 dB. Good agreements between simulated and measured results are achieved, which successfully verifies the proposed design method of diplexers.

The paper presents the results of studying the acoustic characteristics of special X-ray acousto-optical elements designed for precision control of X-ray beam parameters with time resolution. X-ray measurements revealed a number of specific features of oscillations of X-ray acoustic elements not exhibited in standard electromechanical measurements. The existence of these features is confirmed by numerical calculations computations of the acoustic fields in this type of elements. [ABSTRACT FROM AUTHOR]

We report the small-signal modulation characteristics of a monolithic dual resonator vertical cavity surface emitting laser. The modulation response is described by a system of rate equations with two independent carrier populations and a single longitudinal optical mode. The independent optical overlaps and differential gains of the two active regions can each be adjusted to maximize the output response. We show that under certain conditions, the composite resonator may achieve a higher bandwidth than a single cavity laser with the same photon density. We find the relaxation oscillation frequency to depend mainly on the total photon density and not the individual currents in the two cavities. With appropriate current injection, the composite resonator laser achieves a maximum -3-dB bandwidth of 12.5 GHz and a maximum modulation current efficiency factor of approximately 5 GHz/ma1/2. [ABSTRACT FROM AUTHOR]

We investigate the output characteristics from 10°C to 160°C of a monolithic dual-resonator vertical-cavity laser composed of three distributed Bragg reflector mirrors that separate two nominally identical optical cavities. The light output from the top ion-implanted cavity under forward bias is partitioned into two orthogonal polarizations of the fundamental transverse mode. A reverse bias of sufficient magnitude applied to the bottom oxide cavity causes the abrupt suppression of the dominant polarization and simultaneous emergence of the orthogonal polarization, consistent with wavelength dependent electroabsorptive loss in the re verse biased quantum wells of the oxide-confined cavity. We calculate the internal loss as a function of reverse bias and temperature, and characterize the polarization properties of the device based on the temperature dependence of the laser output The polarization switching is consistent with Increasing absorption with Increasing temperature and decreasing absorption at longer wavelengths. [ABSTRACT FROM AUTHOR]