Low-Cost High-Sensitivity Strain and Temperature Sensing Using Graded-Index Multimode Fibers

We report a low-loss, low-cost high-sensitivity all-fiber strain and temperature sensor based on mode interference in graded-index multimode fibers. Blueshifts with strain and temperature sensitivities of 18.6 pm/microstrain and 58.5 pm/°C have been observed. Experimental results show that smaller core diameter graded-index fibers display greater strain-induced peak wavelength shifts than larger core diameter fibers

Self-adaptive GA, quantitative semantic similarity measures and ontology-based text clustering

As the common clustering algorithms use vector space model (VSM) to represent document, the conceptual relationships between related terms which do not co-occur literally are ignored. A genetic algorithm-based clustering technique, named GA clustering, in conjunction with ontology is proposed in this article to overcome this problem. In general, the ontology measures can be partitioned into two categories: thesaurus-based methods and corpus-based methods. We take advantage of the hierarchical structure and the broad coverage taxonomy of Wordnet as the thesaurus-based ontology. However, the corpus-based method is rather complicated to handle in practical application. We propose a transformed latent semantic analysis (LSA) model as the corpus-based method in this paper. Moreover, two hybrid strategies, the combinations of the various similarity measures, are implemented in the clustering experiments. The results show that our GA clustering algorithm, in conjunction with the thesaurus-based and the LSA-based method, apparently outperforms that with other similarity measures. Moreover, the superiority of the GA clustering algorithm proposed over the commonly used k-means algorithm and the standard GA is demonstrated by the improvements of the clustering performance

Measurement of the squeezed vacuum state by a bichromatic local oscillator

We present the experimental measurement of a squeezed vacuum state by means of a bichromatic local oscillator (BLO). A pair of local oscillators at $\pm$5 MHz around the central frequency $\omega_{0}$ of the fundamental field with equal power are generated by three acousto-optic modulators and phase-locked, which are used as a BLO. The squeezed vacuum light are detected by a phase-sensitive balanced-homodyne detection with a BLO. The baseband signal around $\omega_{0}$ combined with a broad squeezed field can be detected with the sensitivity below the shot-noise limit, in which the baseband signal is shifted to the vicinity of 5 MHz (the half of the BLO separation). This work has the important applications in quantum state measurement and quantum informatio