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No description available.

The finite-Difference Time Domain method (FDTD) is to derive the discrete form of the Maxwell¡¦s equations by second-order central difference with the electromagnetic distribution of the Yee space lattice, and computes the value of the electric field and magnetic field in the simulation space by using leapfrog for time derivatives. This method is also different with the frequency domain method which needs to analyze its value individually (ex. Finite Element method). The frequency domain method needs to take a long time for analyzing the response on each spectrum point when the bandwidth is very wide. The advantage of time domain analysis is to obtain the complete frequency response from the simulation value through Fourier Transform method. It¡¦s impossible to combine the electromagnetic analysis with the lumped circuit simulation in current simulation CAD. Thereby the performance of the simulation result and the practical implementation always occurs error because of the lake of the consideration. The FDTD method is the full-wave algorithm which can also simulate the lump element, nonlinear element or active element in simulation space by linking to SPICE or S-parameter. The purpose of this thesis is to develop the method for simulating microwave circuit, and to verify the credibility between the equivalent source method and the S-parameter method in FDTD by the simulation of active antenna and low-noise amplifier.

The finite-Difference Time Domain method (FDTD) derives the discrete form of the Maxwell¡¦s equations with second-order central difference with the electromagnetic distribution of the Yee space lattice, and computes the value of the electric field and magnetic field in the simulation space using leapfrog for time derivatives. This method is different from the frequency domain method which needs to analyze its value individually (ex. Finite Element method). The frequency domain method needs to take a long time for analyzing the response on each spectrum point when the bandwidth is very wide. The advantage of time domain analysis is to obtain the complete frequency response from the simulation value through Fourier Transform method. It¡¦s difficult to combine the electromagnetic analysis with the lumped circuit simulation in current simulation CAD. Thereby the performance of the simulation result and the practical implementation always causes error. The FDTD method is the full-wave algorithm which can also simulate the lump element, nonlinear element or active element in simulation space by linking to SPICE or S-parameter. In this dissertation, an efficient scheme for processing arbitrary one-port devices in the finite-difference time-domain (FDTD) method is proposed. Generally speaking, methods invoking analytic pre-processing of the device¡¦s V-I relations (admittance or impedance) are computationally more efficient than methods employing numerical procedure to iteratively process the device at each time step. The accuracy of the proposed method is verified by comparison with results from the equivalent current-source method and is numerically stable.

The recent advancement of superconducting nano devices has allowed for making a Superconducting Nanowire Single Photon Detector (SNSPD), whose extraordinary features have strongly motivated the research community to exploit it in many practical applications. In this thesis, an experimental setup for testing the SNSPD has been established. It contains an in-house packaging that meets the requirements of RF/microwave and optoelectronic characterizations. The quantum efficiency and detection efficiency measurements have confirmed that our approach is satisfactory. The dark count performance has reached the anticipated level. The factors affecting rise and fall times of the photoresponses are addressed. Based on the successful setup, the characterizations including dc, small signal ac measurements have been undertaken. The measurements are aimed at quantitatively investigating Cooper pair density in the superconducting nanowire. The experimental method involves a two-step, small signal S-parameter measurement either in the presence or absence of optical powers. The subsequent measurements by varying the temperature and dc bias current have achieved remarkable understanding on the physical properties of SNSPD nanowires. Then, the electrically induced nonlinearity is studied via the large signal RF and Microwave measurements. The experiments are a set of one-tone and two-tone measurements, in which either the RF driving power is varied at a fixed frequency, or vice versa. Two major nonlinear microwave circuit analysis methods, i.e. time-domain transient and hybrid-domain harmonic balance analysis, are employed. The simulation result reveals the optimized conditions of reaching the desired nonlinearity. Finally, we have successfully measured the optoelectronic mixing products in an electrically pumped optoelectronic mixer, which has identical structures as that of the SNSPD. The experiments confirm that this mixer is not only sensitive to the classical light intensities, but also to that of the single photon level. Meanwhile, the quantum conversion matrices is derived to interpret the quantum optoelectronic mixing effects.

The recent advancement of superconducting nano devices has allowed for making a Superconducting Nanowire Single Photon Detector (SNSPD), whose extraordinary features have strongly motivated the research community to exploit it in many practical applications. In this thesis, an experimental setup for testing the SNSPD has been established. It contains an in-house packaging that meets the requirements of RF/microwave and optoelectronic characterizations. The quantum efficiency and detection efficiency measurements have confirmed that our approach is satisfactory. The dark count performance has reached the anticipated level. The factors affecting rise and fall times of the photoresponses are addressed. Based on the successful setup, the characterizations including dc, small signal ac measurements have been undertaken. The measurements are aimed at quantitatively investigating Cooper pair density in the superconducting nanowire. The experimental method involves a two-step, small signal S-parameter measurement either in the presence or absence of optical powers. The subsequent measurements by varying the temperature and dc bias current have achieved remarkable understanding on the physical properties of SNSPD nanowires. Then, the electrically induced nonlinearity is studied via the large signal RF and Microwave measurements. The experiments are a set of one-tone and two-tone measurements, in which either the RF driving power is varied at a fixed frequency, or vice versa. Two major nonlinear microwave circuit analysis methods, i.e. time-domain transient and hybrid-domain harmonic balance analysis, are employed. The simulation result reveals the optimized conditions of reaching the desired nonlinearity. Finally, we have successfully measured the optoelectronic mixing products in an electrically pumped optoelectronic mixer, which has identical structures as that of the SNSPD. The experiments confirm that this mixer is not only sensitive to the classical light intensities, but also to that of the single photon level. Meanwhile, the quantum conversion matrices is derived to interpret the quantum optoelectronic mixing effects.