Thermo-optical properties of silicon nitride Mach-Zehnder interferometer for the on-chip quantum random number generator

Here we study the thermo-optical properties of an on-chip silicon nitride Mach-Zehnder interferometer (MZI). The spectral shift of the MZI is associated with a change in the chip temperature. This can be explained by a change in the splitting ratio of the directional couplers, as well as a significant change in phase difference between waveguide arms. We experimentally found a phase shift of 2π when heated by 1.67 °C and changes in resonant wavelength at different temperatures (dλ/dT) equal 12.0 pm/°C, theoretically obtained a formula for an arbitrary splitting ratio of the directional couplers in an MZI, and determined the temperature stability required to the device operation inside a quantum cryptography system.

Efficient Data-Mining Algorithm for Predicting Heart Disease Based on an Angiographic Test

Background: The computerised classification and prediction of heart disease can be useful for medical personnel for the purpose of fast diagnosis with accurate results. This study presents an efficient classification method for predicting heart disease using a data-mining algorithm. Methods: The algorithm utilises the weighted support vector machine method for efficient classification of heart disease based on a binary response that indicates the presence or absence of heart disease as the result of an angiographic test. The optimal values of the support vector machine and the Radial Basis Function kernel parameters for the heart disease classification were determined via a 10-fold cross-validation method. The heart disease data was partitioned into training and testing sets using different percentages of the splitting ratio. Each of the training sets was used in training the classification method while the predictive power of the method was evaluated on each of the test sets using the Monte-Carlo cross-validation resampling technique. The effect of different percentages of the splitting ratio on the method was also observed. Results: The misclassification error rate was used to compare the performance of the method with three selected machine learning methods and was observed that the proposed method performs best over others in all cases considered. Conclusion: Finally, the results illustrate that the classification algorithm presented can effectively predict the heart disease status of an individual based on the results of an angiographic test.

Power Splitting and Source-Relay Selection in Energy Harvesting Wireless Network

In this paper, we consider an energy-harvesting (EH) relay network composing of multiple sources, a destination and multiple EH decode-and-forward (DF) relays. The EH relays all equip with a power splitter to divide the received signal power into two parts, one for information decoding and the remaining for signal relaying. The power splitting ratio (PSR) depicts the trade-off between the relaying energy and decoding energy. We propose an optimal power splitting and joint source-relay selection (OPS-JSRS) scheme where the optimal power-splitting ratio is obtained and the best source-relay pair is selected to transmit the message. For the purpose of comparison, we examine the optimal power splitting and round-robin (OPS-RR) scheme and the traditional power splitting and joint source-relay selection (TPS-JSRS) scheme. The exact and asymptotic closed-form expressions of outage probability for OPS-RR, TPS-JSRS and OPS-JSRS schemes are derived. Numerical results show that OPS-JSRS scheme is better than OPS-RR and TPS-JSRS schemes in terms of outage probability, explaining the superiority of the proposed OPS-JSRS scheme. Additionally, outage probability performance of OPS-JSRS scheme can be improved by increasing the number of sources and relays.

All-Dielectric Metasurface-Based Beam Splitter with Arbitrary Splitting Ratio

The development of optical systems is heading to multi-branch circuit design and miniaturization. A beam splitter is a common device for dividing an incident beam into two separate beams. Conventional beam splitters are constructed using coated prisms or glass plate. Their bulky size, right-angled output direction, and fixed splitting ratio greatly limit the design of optical arrangement and also hinder the system integration. Here, an all-dielectric metasurface composed of symmetric nano-rings as a beam splitter are designed by Finite-Difference Time-Domain method. By changing the inner and outer radiuses of the nano-rings, the wavefront phase of the emergence beam can be adjusted to form a phase gradient, and the incident beam of arbitrary polarization is divided into two beams according to the designed transmittance and angle. The initial phase of the emergence beam can be changed by adjusting the refractive index of the substrate or adding the silicon film to the substrate, and the splitting ratio can be adjusted from 0.5:1 to 1:1. The simulation demonstrates that the metasurface-based beam splitter is independent of polarization and the power efficiency is over 92% with a compact area of 33.6 μm × 33.6 μm. This compact metasurface-based beam splitter has promising potential for enabling new types of compact optical systems and advancing metasurface-based functional integrated photonic applications.