This paper presents a technique for high-accuracy correspondence search between stereo images using 1D Band-Limited Phase-Only Correlation(BLPOC). The stereo correspondence search can be reduced to 1D search through image rectification. However, we usually employ block matching with 2D rectangular image blocks for finding the best matching point. In this paper, we propose the use of 1D BLPOC instead of 2D block matching for correspondence search. The use of 1D BLPOC makes possible significant reduction in computational cost without sacrificing reconstruction accuracy. The resulting reconstruction accuracy is comparable with 2D POC-based method, and is much higher than SAD/SSD-based methods.
We present the modeling and experiment on the intensity-dependent phase shift of a nonlinear optical phase-shifter based on vertical micro-cavity saturable absorber for high-speed response. We demonstrated the 25ps transient response with a large negative nonlinear phase shift of over -0.7 radian. Our device would enable us to control the phase of high speed optical pulses including the compensation of fiber nonlinear effects in optical domain.
Using biometrics to authenticate a person's identity has several advantages over the present practices of Personal Identification Numbers or passwords. To gain maximum security in the authentication system using biometrics, the computation of the authentication as well as the store of the biometric template has to take place in a smart card. However, it is challenging to integrate biometrics into a smart card because of limited resources such as processing power and memory space. In this paper, we propose an area-time-accuracy efficient hardware design for a fingerprint matching system, which can be integrated into smart card chips. Experimental results show that the match operation can be completed in real time (190ms) on the proposed hardware requiring 36K gates (2.4mm2 silicon area by using 0.25µm CMOS technology). Also, an Equal Error Rate (EER) of 3.8% can be obtained by using the proposed hardware solution. For the same operation, a previous software solution with a memory-efficient data structure could be executed only on a state-of-the-art, high-cost smart card and provide an EER of 6.0%.
In this paper, we consider interactive nonlinear problem of multiple users in cognitive radio system. A new model that represents a cognitive radio system with N pairs of nonlinear transmitters and receivers is suggested. The model is represented with a baseband equivalent multi-input system based on complex Taylor series and weight functions. The power spectral density (PSD) of the received signal is analytically extracted using the autocorrelation function of the model output. The error vector magnitude (EVM) degradation due to interactive nonlinear problem is also analyzed. The spectral and EVM degradation analysis are verified by comparing the analytical results with the simulated ones.
We designed a composite resonator VCSEL using a VCSEL chip and a concave external mirror for mode-locking to produce optical clock signals and demonstrated the operation experimentally. A very low threshold current was successfully realized by using a proper reflectivity of VCSEL and the external mirror and by achieving efficient feedback using a concave external mirror. Using a concave mirror with the curvature radius of 14.12mm, sub-harmonic active mode-locking was achieved at a repetition rate of 10.56GHz, which corresponded to the external cavity length.
In order to realize flexible bandwidth allocation in access networks with bit rates of 10Gb/s or more, transmitting data by parallel streams with different wavelengths is an attractive approach. In such systems, the timing skew induced by fiber dispersion is the critical problem. This paper proposes a skew compensation LSI for an optical access system based on power splitter based wavelength division multiplexing passive optical network (PS-WDM-PON). The LSI can compensate timing skew of more than 9.6ns with 82ps resolution; experiments show that transmission distance of 24km are possible if the bit rate of each wavelength is 2.5Gbit/s and all wavelengths lie within 20nm.