A rigorous method, which called the three plane mode- matching (TPMM) technique, for modeling E-plane T-junction is used to design a millimeter-wave diplexer with E-plane all-metal filters at V-band, and the modeling values presented in this paper are agreed well with the results published in the literature.
An electrically tunable grating coupler is designed and numerically demonstrated. With a lateral p-i-n diode embedded, the optical spectrum of coupling efficiency can be tuned with the applied voltage. To simulate the coupling spectra response with bias voltage, the optical simulation and electrical simulation are carried out with the commercial software Lumerical Finite-Difference Time-Domain Solutions and Synopsys Sentaurus TCAD. Due to the dual effect of spectrum shift and optical loss, the coupling efficiency spectrum can be greatly modulated. With a bias voltage of 2 V, the resulting spectrum shift is 47.5 nm and the peak coupling efficiency at the designed wavelength center can be modulated from 52% to 10%. In addition, the electrical tuning can be used for compensation of postassembly spectrum shift. The effects of the incident angle error and epoxy curing process are discussed. According to our simulation results, tuning voltages of 1 and 2 V are enough to compensate for the incident angle error of 2.5 deg and 3.5 deg, respectively. For the spectrum shift caused by epoxy bonding, the required tuning voltage is as low as 0.82 V. Though it brings additional optical loss, the tuning technique shows interesting prospects in postassembly coupling optimization or channel equalization.
Nowadays, high power LED is often packaged with flip chip method. The gold bump is usually made by electroplating
or gold evaporation, which cause the environment pollution and material waste. A gold wire bump manufacture
technology for high power LED flip chip is described in this paper. The wire bond device is used and different bump
making parameters, such as weld temperature, pressure and ultrasonic power, are optimized through experiments. At the
same time, a new bump wire tail height managing process is introduced. The gold wire bump with this method height
difference keep in 3 micrometers and which is convenient for flip chip. Then, rapid annealing is taken to make sure the
gold wire bump has a well adherence to the wafer. At last, the bump weld result is tested and the bump invalidation is
analyzed with the SEM. The bonding force between bump and wafer more than 10 grams. The flip chip high power LED
with gold wire bump has low forth voltage and heat resistance. All of above proved that the gold wire bump is
convenient and reliable for high power flip chip LED.
A new simplified heterojunction phototransistor (HPT) circuit model is given in this paper. Most of papers use Ebers-Moll model to describe the optical-electrical relations of HPT. Which is a physical based model and must be changed with different device structure. In this paper, an empirical model is employed. This model mainly formed by three parts: the photo current (I<sub>ph</sub>), base current (I<sub>b</sub>) and collector current(I<sub>c</sub>). A dependent current source is used to model the photo current between the collector and base. The photo current can be different from different optical power. Ib are depend on base-emitter voltage while Ic is a function of collector-emitter voltage, I<sub>b</sub> and I<sub>ph</sub>. Contrast with the Ebers-moll model, the empirical model greatly reduced the complexity of the circuit. The model parameters are extracted on measured Ic-Vce and gummel plots. Then, dates in some documents were used to test the empirical model. There is a good agreement with the measured results.
We have measured the I-V characteristics of the Resonant tunneling diode (RTD) fabricated by ourselves. Basing on the measured results, several questions have been analyzed and discussed: (1) Temperature effects on I-V characteristics; (2) “The Apparent positive resistance phenomena” in negative resistance region. The analysis and discussion on above questions are very useful and helpful for design and fabrication of RTD.