Practical aspects of fiber optical parametric amplifiers for optical communication

Invited PaperFiber optical parametric amplifiers (OPAs) are based on the third-order nonlinear susceptibility of glass fibers. If two strong pumps and a weak signal are fed into a fiber, an idler is generated. Signal and idler can grow together if pump power is high enough, and phase matching occurs. Until recently, impressive performance of fiber OPAs has been demonstrated in different respects. However, secondary effects should be addressed before OPAs can be utilized in practical applications. Here we report some of these effects, either exploiting them as in the parametric processor such as optical logic gates, inverted and non-inverted wavelength converter, and ultra-wideband monocycle and doublet pulses generator, or suppressing them as in the optical amplifier for WDM systems.published_or_final_versionThe 9th International Conference on Optical Communications and Networks (ICOCN 2010), Nanjing, China, 24-27 October 2010. In Proceedings of the 9th ICOCN, 2010, p. 299-30

Reliable and fast human body tracking under information deficiency

Session MA-4 System Identification and Pattern Recognition IHuman body tracking is useful in applications like medical diagnostic, human computer interface, visual surveillance etc. In most cases, only rough position of the target is needed, and blob tracking can be used. The blob region is located within a searching window, which is shifted and resized in each frame based on previous observations. The observations are the locations of the blob in the frames, and are fed into an estimator for predicting the position and the size of the searching window. However, a blob region is regarded as a noisy observation, and the information provided by the blob observation is deficient for most estimators to work well. In this paper, a reliable and efficient estimation algorithm using wavelet is proposed to track human body under information deficiency. The human body is located roughly within a small searching window using color and motion as heuristics. The location and the size of the searching window are estimated using the proposed wavelet estimation scheme. Experimental results show that human body can be tracked accurately and efficiently using the proposed method. The tracker works well in various conditions like clutter background, and background with distractors.published_or_final_versionThe 2003 IEEE Intelligent Automation Conference (2003年中国智能自动化会议), Hong Kong, 15-17 December 2003. In Proceedings of the IEEE Intelligent Automation Conference, 2003, p. 491-49

Second-order effects in fiber optical parametric amplifier

Until recently, impressive performance of fiber optical parametric amplifiers (OPAs) has been demonstrated in different respects. However, second-order effects should be addressed before OPAs can be practical. Here we report some of these effects, either exploiting them as in the parametric processor or suppressing them as in the optical amplifier. ©2009 Optical Society of America.published_or_final_versio

Robust image segmentation by texture sensitive snake under low contrast environment

Robust image segmentation plays an important role in a wide range of daily applications, like visual surveillance system, computer-aided medical diagnosis, etc. Although commonly used image segmentation methods based on pixel intensity and texture can help finding the boundary of targets with sharp edges or distinguished textures, they may not be applied to images with poor quality and low contrast. Medical images, images captured from web cam and images taken under dim light are examples of images with low contrast and with heavy noise. To handle these types of images, we proposed a new segmentation method based on texture clustering and snake fitting. Experimental results show that targets in both artificial images and medical images, which are of low contrast and heavy noise, can be segmented from the background accurately. This segmentation method provides alternatives to the users so that they can keep using imaging device with low quality outputs while having good quality of image analysis result.postprintThe International Conference on Informatics in Control, Automation and Robotics, Setúbal, Portugal, 25-28 August 2004. In Proceedings of the International Conference on Informatics in Control, Automation and Robotics, 2004, p. 430-43

Nanosecond optical parametric oscillator based on highly-nonlinear dispersion-shifted fiber

We demonstrate a fully fiber-integrated tunable nanosecond optical parametric oscillator based on 50-m highly-nonlinear fiber with tuning range from 1433 nm to 1490 nm and from 1625 nm to 1685 nm by tuning the pump wavelength between 1549 nm and 1555 nm. © 2009 IEEE.published_or_final_versio

Fast and reliable recognition of human motion from motion trajectories using wavelet analysis

Recognition of human motion provides hints to understand human activities and gives opportunities to the development of new human-computer interface. Recent studies, however, are limited to extracting motion history image and recognizing gesture or locomotion of human body parts. Although the approach employed, i.e. the transformation of the 3D space-time (x-y-t) analysis to the 2D image analysis, is faster than analyzing 3D motion feature, it is less accurate and less robust in nature. In this paper, a fast trajectory-classification algorithm for interpreting movement of human body parts using wavelet analysis is proposed to increase the accuracy and robustness of human motion recognition. By tracking human body in real time, the motion trajectory (x-y-t) can be extracted. The motion trajectory is then broken down into wavelets that form a set of wavelet features. Classification based on the wavelet features can then be done to interpret the human motion. An online hand drawing digit recognition system was built using the proposed algorithm. Experiments show that the proposed algorithm is able to recognize digits from human movement accurately in real time.postprintThe 2004 IFIP International Conference on Artificial Intelligence Applications and Innovation, Toulouse, France, 22-27 August 2004. In Proceedings of the IFIP International Conference on Artificial Intelligence Applications and Innovation, 2004, p. 1-1

Dispersion-Tuned Harmonically Mode-Locked Fiber Optical Parametric Oscillator

The stable operation of a high-repetition-rate dispersion-tuned harmonically mode-locked fiber-optical parametric oscillator (FOPO) is demonstrated for the first time to the best of our knowledge. The experimental results match well with the theory. By introducing large cavity dispersion, the round-trip delay can vary with wavelength. Thus the cavity can be synchronized with the modulation frequency of an external clock passively. The FOPO can be tuned simply by adjusting the modulation frequency. A stable 10-GHz pulse train is obtained over 6-nm tuning range for each of the signal and idler.published_or_final_versio

Relatively-paired space analysis

Session 11: Segmentation & FeaturesDiscovering a latent common space between different modalities plays an important role in cross-modality pattern recognition. Existing techniques often require absolutely paired observations as training data, and are incapable of capturing more general semantic relationships between cross-modality observations. This greatly limits their applications. In this paper, we propose a general framework for learning a latent common space from relatively-paired observations (i.e., two observations from different modalities are more-likely-paired than another two). Relative-pairing information is encoded using relative proximities of observations in the latent common space. By building a discriminative model and maximizing a distance margin, a projection function that maps observations into the latent common space is learned for each modality. Cross-modality pattern recognition can then be carried out in the latent common space. To evaluate its performance, the proposed framework has been applied to cross-pose face recognition and feature fusion. Experimental results demonstrate that the proposed framework outperforms other state-of-the-art approaches.postprin

Frequency swept fiber ring laser based on optical parametric process with single-longitudinal-mode operation

A stable and wavelength-tunable single-longitudinal-mode (SLM) oscillation with sweeping rate of 1.17 kHz based on a fiber-optical parametric oscillator (FOPO) is proposed and demonstrated. In order to perform sweeping SLM operations, three types of filters, a fiber Fabry-Pérot tunable filter (FFP-TF), a subring cavity, and an autotracking filter which is formed by an unpumped erbium-doped fiber (EDF), are incorporated inside the cavity. The output of the laser can be swept continuously from 1530 to 1543 nm and 1569 to 1584 nm with the average output power exceeding 3 dBm. The short-term linewidth of the laser output measured by self-homodyne method is about 66.6 kHz with a side-mode suppression ratio of 60 dB at 1538 nm. © 2006 IEEE.published_or_final_versio

Phase-inverted sidelobe-annihilated optical coherence tomography to break through the temporal diffraction limit

Understand the tomography system as a temporal microscopy by space-time duality, a simple adjustment was performed on a conventional swept-source optical coherence tomography (SS-OCT), and achieved sharper resolution (~4 μm) for the single layer measurement. © 2015 OSApostprin