In order to achieve electrically pumped plasmon nano lasers, several structures, materials and methods, have been proposed recently. However, there is still a long way to find out a reliable appropriate on-chip plasmon source for commercial plasmonic integrated circuits. In this paper, a new waveguide integrated nanocavity plasmon laser is proposed for 1550 nm free-space wavelength. Due to its significant field confinement resulted by the metal strip structure and strong interaction of plasmonic modes with the germanium quantum wells and as a result a considerable Purcell factor about 291, this structure has a remarkable output performance. Using semi-classical rate equations in combination with finite difference time domain (FDTD) cavity mode analysis, the output performance measures are estimated and confirmed with respect to various physical models and simulation tools. Simulation results for this tiny structure (0.073 µm 2 area) show a 2.8µW output power with 10µA injection current and about 4.16mW output power with the threshold pump current of 27mA while maintaining its performance in a wide modulation bandwidth of 178GHz.
In this paper, we will introduce a new designed direct conversion terahertz detector and we will compare its characteristics with a prefabricated design in order to obtain better performance of our new proposed design. Differences between our new work and prefabricated device are in both physical structure by introducing an exponentially graded base SiGe-HBT instead of linearly graded ones, and configuration of components by means of merging two transistor of the initial common base structure into a single transistor with two base contacts, which equivalent to two transistors in common emitter configuration. New proposed detector, at first will be analyzed with a compact circuit model and then for more accurate analysis, two dimensional carrier transport analysis will be performed with numerical methods. Comparison of new and prefabricated detector will be done by simulation of both new and prefabricated devices with the same simulator. Because of only a slight change in transistor physical structure, if our simulation results and previous empirical data have a good matching for prefabricated device then with a high degree of precision we can claim our comparison is verified, but of course, for better confirmation of our ideas, fabrication and experimental measurements should be done in the next steps. Responsivity and minimum noise equivalent power of new detector are about 4.9A/W and 6.5pW/Hz1/2 respectively, while these characteristics for prefabricated detector, are about 1A/W and 50pW/Hz1/2 respectively. Also about 231µW/pixel decrement in power consumption for the same responsivity, and a same bandwidth have been achieved.
In order to improve the performance of a pre-designed direct conversion terahertz detector which is implemented in a 0.25 m-SiGe-BiCMOS process, we propose some slight modifications in the bipolar section of the SiGe device physical design. Comparison of our new proposed device and the previously reported device is done by SILVACO TCAD software simulation and we have used previous experimentally reported data to confirm our software simulations. Our proposed modifications in device structural design show a present device responsivity improvement of about 10% from 1 to 1.1 A/W while the bandwidth improvement is about 218 GHz. The minimum noise equivalent power at detector output is increased by about 14.3% and finally power consumption per pixel at the maximum responsivity is decreased by about 5%.
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