Monolithically integrated four-channel distributed feedback (DFB) laser array has been fabricated by metal organic vapor phase epitaxy (MOVPE) selective area growth for 1.55µm coarse-wavelength division multiplexing (CWDM) systems. Wide-stripe MOVPE selective area growth and electron-beam lithography are used to obtain wide CWDM channel spacing of 20nm. Optical outputs from the simultaneously biased four DFB lasers are combined via an integrated multimode interference coupler before coupled to a single mode fiber. Compared to hybrid integration of discrete lasers, monolithic integration of laser array on a single substrate simplifies optical alignment and packaging.
A switched capacitor bandgap voltage reference circuit capable of sub-1-V operation is presented. The proposed circuit generates a sub-1-V reference voltage with a switched capacitor operation, offering several performance advantages over the current-mode sub-1-V counterpart. The proposed design provides an improved supply rejection and outperforms in the presence of process variation. In addition, the circuit does not require a start-up circuit and the associating trimming circuitry is simplistic and cost effective. The proposed sub-1-V switched capacitor BGR can be a practical sub-1-V reference candidate in ultra deep sub-micron CMOS processes.
Nonlinear characteristics of SRD are analyzed. A model of SRD for simulation is proposed based on dynamic capacitor and pn diode, which can be used in ADS software. A method of producing UWB monocycle short pulse based on SRD and Schottky diode is proposed and analyzed theoretically. The UWB signal generation produces monocycle pulse with the width of 400ps and the p-p amplitude of 15V. The simulated result meets the tested result, which proves the veracity of the new model of SRD.
This paper proposed an Ant-based contention resolution scheme for the slotted optical packets switched (OPS) networks. The proposed contention resolution schemes are shown to be effective to resolve packet contention and to achieve good performance by using minimum number of fiber delay lines (FDL). Moreover, the cell loss rate is improved by 10% to 40% under various traffic loads using the proposed scheme.
We propose a novel optical switching system equipped with shared wavelength converters with electrical buffers. Simulation results show that the proposed system significantly reduces the blocking probability below 10-6 with low buffering delay. We present benefits of the proposed switching system compared with the conventional dedicated wavelength converter scheme in terms of blocking probability and average delay time. The proposed switching system is believed to be a technoeconomically feasible and implementable solution for optical packet/burst switching with current optical technologies.