We propose a novel hollow waveguide optical switch composed of a multi-mode interference (MMI) coupler with a variable air core. The numerical simulation of the proposed optical switch is carried out for investigating switch performances. Switching operation can be obtained by mechanical displacement of the air core of an MMI hollow waveguide. A hollow waveguide consists of Ta2O5/SiO2 multilayer mirrors for optical confinement. The result shows a possibility of switching of about 99.5% optical power fraction with a switching length of 500µm and a small displacement (ΔDcore=2.5µm) of an air core thickness.
A high-sensitive CMOS photosensor based on a pulse frequency modulation (PFM) scheme is presented. We propose and demonstrate the high-sensitive PFM photosensor, whose output frequency is proportionate to the incident light intensity, that utilizes MOS interface-trap charge pumping (ITCP) as a frequency-controlled ultra-low current. The proposed pixel sensor consists of only 4 transistors: a transistor as an ultra-low current source; a sense amplifier transistor; a selection transistor; and, a reset transistor. The prototype device is fabricated using 0.6-µm standard CMOS technology. High sensitivity 4.0 × 105Hz/(W·m-2), which is larger than two orders of magnitude compared to previous works, was obtained.
An innovative phase detector for burst mode data recovery is presented. The problem of the random nature of the data is handled via the specific data recovery architecture, where a time-advanced version of the input data is fed to a third phase detector input. The phase detector was designed in a 0.13µm CMOS technology. Simulation results demonstrate its effectiveness for the recovery of burst mode NRZ data at 1.25Gbit/s.
Excess loop delay in continuous time (CT) Delta-Sigma modulators (DSM), as a result of the limited DAC response time, leads to SNR degradation so that the optimal tuning of the system will be impossible. In order to solve this problem, this paper proposes a novel return to-zero feedback insertion method. To verify the analytical results extracted in this paper, a second order CT DSM is simulated.
Fingerprint matching is one of the most important problems in Fingerprint Identification System (AFIS). In this paper a new method of the reference point alignment has been presented. A new approach of reference point localization is based on so-called identification masks which have been composed on the basis of analysis of biometric characteristic of human finger. Construction of such masks has been presented. Experiments show that our approach locates a unique reference point with high accuracy for all types of fingerprints. Generally, fingerprint matching consists with three steps: core (reference) point detection, filter the image using a bank Gabor filters, and comparison with imprint pattern. It seems, that today, the Gabor filtering gives the best results in fingerprint recognition. The proposed method was evaluated and tested on various fingerprint images, included in the FVC2000 fingerprint database. Performed results with representative investigations have been compared.
An image contrast enhancement algorithms for BDCT (Block Discrete Cosine Transform) based compressed images is presented. Contrast enhancement is achieved by modifying the quantized DCT coefficients based on a contrast measure defined within the DCT domain. The performance is compared with other methods and better visual quality is obtained.