Current Issue : October - December Volume : 2020 Issue Number : 4 Articles : 6 Articles
This paper presents a method for gas concentration determination based on the measurement of the refractive index dispersion of a gas near the gas resonance in the near-infrared region (NIR). The gas refractive index dispersion line shape is reconstructed from the variation in the spectral interference fringesâ?? periods, which are generated by a low-finesse Fabry-Perot interferometer during the DFB diodeâ??s linear-over-time optical frequency sweep around the gas resonance frequency. The entire sensing system was modeled and then verified experimentally, for an example of a low concentration methane-air mixture. We demonstrate experimentally a refractive index dispersion measurement resolution of ..............
Recently, the demand for accuracy measurement of microstructures has been remarkable.\nWe have been developing a measurement system for microstructures using a stylus made of an\noptical fiber and prisms. In this measurement system, the oblique irradiation of the laser beam was\nemployed to detect the displacement of the stylus shaft generated by contact between the stylus tip\nand the measured surface, and to expand the measurable area and depth. After these evaluations,\nwe discovered that the sensitivity was enhanced with the increase in the incident angle of the laser\nbeam on the stylus shaft. Therefore, in this study, we focus on the effect of the incident angle of light\non the measurement sensitivity. First, the enhancement sensitivity is confirmed by using the basic\nexperimental apparatus. Next, the relationship between the incident angle of the laser beam and the\nsensitivity is theoretically examined using the 3D ray-tracing method. Finally, the factor of the\nsensitivity enhancement is analyzed using the same method. As a result, it was confirmed that the\nsensitivity was enhanced with the increase in the incident angle of the laser beam on the stylus shaft....
Recently, there has been tremendous research studies in optical neural networks that could complete comparatively complex\ncomputation by optical characteristic with much more fewer dissipation than electrical networks. Existed neural networks based\non the optical circuit are structured with an optical grating platform with different diffractive phases at different diffractive points\n(Chen and Zhu, 2019 and Mo et al., 2018). In this study, it proposed a multiwave deep diffractive network with approximately 106\nsynapses, and it is easy to make hardware implementation of neuromorphic networks. In the optical architecture, it can utilize\noptical diffractive characteristic and different wavelengths to perform different tasks. Different wavelengths and different tasks\ninputs are independent of each other. Moreover, we can utilize the characteristic of them to inference several tasks, simultaneously.\nThe results of experiments were demonstrated that the network could get a comparable performance to singlewavelength\nsingle-task. Compared to the multinetwork, single network can save the cost of fabrication with lithography. We train\nthe network on MNISTand MNIST-FASHION which are two different datasets to perform classification..................
To support cloud services, Data Centre Networks (DCNs) are constructed to have many servers and network devices, thus\nincreasing the routing complexity and energy consumption of the DCN. The introduction of optical technology in DCNs gives\nseveral benefits related to routing control and energy efficiency. This paper presents a novel Packet Classification based Optical\ninterconnect (PCOI) architecture for DCN which simplifies the routing process by classifying the packet at the sender rack and\nreduces energy consumption by utilizing the passive optical components. This architecture brings some key benefits to optical\ninterconnects in DCNs which include (i) routing simplicity, (ii) reduced energy consumption, (iii) scalability to large port count,\n(iv) packet loss avoidance, and (v) all-to-one communication support. The packets are classified based on destination rack and are\narranged in the input queues. This paper presents the input and output queuing analysis of the PCOI architecture in terms of\nmathematical analysis, the TCP simulation in NS2, and the physical layer analysis by conducting simulation in OptiSystem. The\npacket loss in the PCOI has been avoided by adopting the input and output queuing model. The output queue of PCOI architecture\nrepresents an M/D/32 queue. The simulation results show that PCOI achieved a significant improvement in terms of\nthroughput and low end-to-end delay. The eye-diagram results show that a good quality optical signal is received at the output,\nshowing a very low Bit Error Rate (BER)....
A theoretical design of a multi-layer for Nd:YAG mirrors resonator is described\nin this work. An output coupler was designed and fabricated by successive\nthin layers to achieve very high transmittance at optical wavelengths\naround 1064 nm for Nd:YAG mirrors resonator. The different film optical\nfilters were used to control the transmittance and reflectance. The three samples\nof dielectric materials composed of HfO2/Y2O3, Sc2O3 + MgO, and Ta2O5\n+ TiO2 were used and compared with each other in transmittance, reflectance,\nfull width at half maximum (FWHM), physical thickness, optical\nthickness, geometric thickness, and incident angles by the software....
Laser diodes (LDs) are widely used in optical wireless communication (OWC) and optical networks, and proper theoretical\nmodels are needed to precisely describe the complicated beam field of LDs. A novel mathematical model is proposed to describe\nthe vectorial field of nonparaxial LD beams. Laser beam propagation is studied using the vector Rayleigh diffraction integrals, and\nthe stationary phase method is used to find the asymptotic expansion of diffraction integral. The far-field distribution of the LD\nbeam in the plane parallel and perpendicular to the junction is considered in detail, and the computed intensity distributions of the\ntheory are compared with the corresponding measurements. This model is precise for single transverse model beam of LDs and\ncan be applied to describe the LD beams in OWC and optical networks....
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