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Mode-division multiplexing is an enabling technique for large-capacity on-chip optical interconnects. Multimode power splitter becomes the subject of interests which is highly desirable. However, challenges still exist for multimode splitter with arbitrary power ratio. Inspired by geometric optics, we demonstrate a series of power splitters based on T-branch waveguide mirrors which consist of subwavelength nanoholes. Arbitrary split ratio can be achieved by modifying the transmittance and reflectance of the waveguide mirrors. The devices can support up to 9 modes from TE0-TE8. For a proof-of-concept demonstration, we fabricate dual-mode splitters with power ratios of 40:60, 30:70 and 20:80. For both TE0 and TE1 modes, the measured excess losses are lower than 0.92 dB, and the crosstalk are all below –14.42 dB within the wavelength range from 1540 to 1580 nm.

Controlling the distribution of solar spectrum in different bands would boost the energy harvesting efficiency and optimize the energy dispatchability. 1D photonic crystal with intrinsic optical band gap can be used to split the solar spectrum for hybrid photovoltaic/thermal solar applications. Here, we designed an efficient solar spectrum optical filter based on a cermet layer, Si/SiO2 1D photonic crystal, and top heterostructure layer. Compared with 1D photonic crystal structure, the 1D photonic crystal heterostructure with top YSZ layer can realize the reflectance of greater than 92% in PV band and the low average reflectance in two thermal bands by tuning the effective impedance of multilayer films. The enhanced reflectance in PV band results from the huge mismatching of impedance between free space and the heterostructure structure. The top dielectric layer can also be extended to other oxides.

In this paper, we propose and simulate a new type of three-dimensional (3D) optical splitter based on multimode interference (MMI) for the wavelength of 1550 nm. The splitter was proposed on the square basis with the width of 20 x 20 µm2 using the IP-Dip polymer as a standard material for 3D laser lithography. We present the optical field distribution in the proposed MMI splitter and its integration possibility on optical fiber. The design is aimed to the possible fabrication process using the 3D laser lithography for forthcoming experiments.

Time-frequency synchronization plays an important role in the construction of solar radio telescopes (such as heliograph and interferometry). In the development of a synchronization system, time-frequency signal is divided and transmitted to each antenna in an array, therefore, the performance of the signal splitting devices determines the quantity of the data. To address this situation, we designed a frequency transmitting system, and conducted a test to compare the phase difference among outputs (10 MHz - 1.4 GHz), and the deterioration of the frequency stability (10 MHz - 1GHz) brought by different splitting devices (fiber splitter and power divider). The following results had been obtained: 1) Phase difference introduced by both fiber splitter and power divider can be restricted in a range of ±4°, and the fiber splitter is rather stable, which indicate that a better imaging effect of heliograph can be achieved when using fiber splitters. 2) Frequency stability deterioration get better (worse) with increasing temperature for fiber splitter (power divider) in the testing frequency range for a short-time sampling (100 ms), and for a long-time sampling (10 min), the frequency stability of different devices is determined by both temperature and signal frequency. By estimating the SNR, the performance of optical splitter is found to be slightly better than power splitter. This article provides a basis for the selection and compensation of frequency transfer system components for integrated aperture heliograph, and provide a feasible solution of the construction of low-cost radioheliograph.

A high-speed moving average integrator in silicon photonics is demonstrated. The integrator is monolithically fabricated with an optical receiver front-end operating at 1550 nm. The design consists of an optical splitter, an optical low-loss delay line to implement a 400 ps delay between the two received bit streams, two SiGe photodiodes, and a 200 fF capacitor. The proposed moving average structure can perform four-bit integration at 10 Gbps. The resulting signal at the output of the integrator is the moving average of the received bit streams. The moving average integrator is validated through measurements and simulations at 2.5 and 5 Gbps. The proposed structure facilitates the development of next generation cost-effective and energy-efficient optical transceivers by exploiting optical time delay and moving average operation in silicon photonics. This mitigates the need for multiple clock phase generation and trans-impedance amplification on the electronic chip.

A method is proposed for transferring the unit of mean power of laser radiation by means of measuring high-intensity power (kilowatts), with the possibility of constant monitoring of the transfer process. A measuring optical power divider for laser radiation has been developed, structurally built in the form of a wedge and permitting, according to the relatively small power of the radiation reflected from the lighted surface of the forward face of the wedge, to determine the radiant power of the beam incident upon the measuring instrument to be calibrated. The proposed method is based on applying the developed divisor in the reference installation and provides for the implementation of three modes of operation of the installation: the mode for determination of the coefficient of equivalence; the mode for determination of the division ratio of the optical splitter; the mode of transfer of the power unit by measurement facilities; and determination of the control parameter of the optical splitter. The transfer process is monitored by measuring the radiant power reflected from the back edge of the wedge, and determining the control parameter. The conditions in which it is advisable to use the proposed mode of determining the division ratio of the optical splitter are given. A special feature of the method under study is the possibility of timely monitoring of the division ratio of the optical splitter, making it possible to estimate in real time the reliability of the process of calibration of measurement instruments. A formula was derived for the metrological traceability of the power measurement results to GET 28-2016. The basic error component errors of the determination of the radiant power arriving at input of the measurement facilities being calibrated are considered. The results of the experimental studies of this method make it possible to confirm that at 10.6 μm wavelength, the total measurement error of the power, expressed as the SD, does not exceed 2.0%. The method can be used in the corresponding secondary standards of the power unit that obtain a unit from the State Special Standard for Mean Power, GET 28-2016.

The working environment of Planar Lightwave Circuit (PLC) optical splitter is complex and diverse. In addition to withstanding the test of environmental temperature changes, the device may also be affected by mechanical shock such as vibration. Through the thermal-vibration coupling online test, it was found that the insertion loss of the PLC optical splitter changes significantly when the vibration test is performed under high temperature and low temperature environment (the maximum insertion loss change was 4.491dB at 75 °C, and 3.941dB at −40°C). In the same temperature environment, the optical performance of the device during the lateral test and the vertical test was more affected by vibration than in the horizontal test. The study of reliability under combined vibration and temperature fields is helpful to understand and improve the ability of devices to work normally in complex environments.

Объект исследования – измерительная система на основе полимерного оптического волокна опрашиваемая смартфоном для измерения пульсовой волны человека. Цель работы – создание дешёвого волоконно-оптического датчика на основе полимерного волокна для регистрации сигнала пульсовой волны и его опрос при помощи смартфона. В Ñ Ð¾Ð´Ðµ работы было создано два Ñ‡ÑƒÐ²ÑÑ‚Ð²Ð¸Ñ‚ÐµÐ»ÑŒÐ½Ñ‹Ñ ÑÐ»ÐµÐ¼ÐµÐ½Ñ‚Ð°, Ð¼Ð¾Ð´ÑƒÐ»Ð¸Ñ€ÑƒÑŽÑ‰Ð¸Ñ Ð¸Ð½Ñ‚ÐµÐ½ÑÐ¸Ð²Ð½Ð¾ÑÑ‚ÑŒ отраженного излучения. С Ð¸Ñ Ð¿Ð¾Ð¼Ð¾Ñ‰ÑŒÑŽ были измерены пульсовые волны на небольшой выборке Ð¸ÑÐ¿Ñ‹Ñ‚ÑƒÐµÐ¼Ñ‹Ñ . Было проведено визуальное сравнение сигналов Ð¿ÑƒÐ»ÑŒÑÐ¾Ð²Ñ‹Ñ Ð²Ð¾Ð»Ð½ и количественное сравнение Ð¸Ñ Ñ Ð°Ñ€Ð°ÐºÑ‚ÐµÑ€Ð¸ÑÑ‚Ð¸Ðº при помощи ÑÐ»ÐµÐ´ÑƒÑŽÑ‰Ð¸Ñ Ð¼ÐµÑ‚Ñ€Ð¸Ðº: соотношение сигнал-шум, повторяемость интервалов волн и повторяемость декомпозиции Ð¿ÑƒÐ»ÑŒÑÐ¾Ð²Ñ‹Ñ Ð²Ð¾Ð»Ð½ на шесть Ð³Ð°ÑƒÑÑÐ¾Ð²Ñ‹Ñ Ñ„ÑƒÐ½ÐºÑ†Ð¸Ð¹. Было показано что, во-Ð¿ÐµÑ€Ð²Ñ‹Ñ , показания первого чувствительного элемента более стабильны, чем второго; во-Ð²Ñ‚Ð¾Ñ€Ñ‹Ñ , сигнал-шум пульсовой волны при опросе датчиков при помощи смартфона в несколько раз выше, чем при опросе при помощи фотодетектора с АЦП; в-Ñ‚Ñ€ÐµÑ‚ÑŒÐ¸Ñ , качество Ñ€ÐµÐ³Ð¸ÑÑ‚Ñ€Ð¸Ñ€ÑƒÐµÐ¼Ñ‹Ñ Ð¿ÑƒÐ»ÑŒÑÐ¾Ð²Ñ‹Ñ Ð²Ð¾Ð»Ð½ при помощи первого чувствительного элемента, опрашиваемого смартфоном не намного уступают таковому для известной ранее дорогостоящей системы с волоконно-оптическим интерферометром Фабри-Перо со спектральным опросом. Результаты работы могут найти применение в медицине для создания Ð½ÐµÐ´Ð¾Ñ€Ð¾Ð³Ð¸Ñ Ð½Ð¾ÑÐ¸Ð¼Ñ‹Ñ Ð¿ÐµÑ€ÑÐ¾Ð½Ð°Ð»ÑŒÐ½Ñ‹Ñ ÑÐ¸ÑÑ‚ÐµÐ¼ мониторинга состояния здоровья человека., The subject of the graduate qualification work is a measuring system based on a polymer optical fiber interrogated by a smartphone to measure a person's pulse wave. The given work is devoted to creating a cheap fiber–optic sensor based on polymer fiber for recording a pulse wave signal and interrogation it using a smartphoneIn the course of the work, two sensitive elements were created that modulate the intensity of reflected radiation. With their help, pulse waves were measured on a small sample of subjects. A visual comparison of pulse wave signals and a quantitative comparison of their characteristics was carried out using the following metrics: signal-to-noise ratio, repeatability of wave intervals and repeatability of the decomposition of pulse waves into six Gaussian functions. It was shown that, firstly, the readings of the first sensing element are more stable than the second; secondly, the pulse wave signal-noise when interrogating sensors using a smartphone is several times higher than when interrogating using a photodetector with an ADC; thirdly, the quality of recorded pulse waves using the first sensor element interrogated by a smartphone is not much inferior to that of a previously known expensive system with a fiber-optic Fabry-Perot interferometer with a spectral interrogation. The results of the work can be used in medicine to create inexpensive wearable personal health monitoring systems.

A high-sensitivity y-splitter, based on thermal ion-exchange waveguide has been studied for biochemical sensing platform applications. Based on the analysis, the ion-exchange waveguide has been simulated and designed by using the finite difference time domain method (FDTD). To realize high-resolution, y-splitter read-out configuration is investigated based on the ion-exchange waveguide with a total height of 0.22 µm and width of 0.5 µm at the operating wavelength between 1500 and 1600 nm. The length of the sensitive window in the y-splitter configuration is 4 µm, where the total length of the y-splitter is 16 µm. In this context, the produced bio-sensor which can be made using the optical waveguide configurations, is providing a cost-effective method for sensing materials such as DNAs. The sensing arm which is covered by the DNA as upper cladding has 0.45 x 10−3 decreasing power in comparison to the reference arm. In this paper, the simulation of the y-splitter optical waveguide has been performed using the ion-exchange technique to detect the DNAs.

Environmental, mechanical and optical reliability are basic premises for application of PLC optical splitters. According to temperature and humidity cycling experiment, it demonstrated that insertion loss of PLC optical splitter varies with temperature. Compared to performance at room temperature, the maximum insertion loss change of device is 0.472 dB at 75 °C, and 0.486 dB at −40 °C. A three-dimensional finite element model of PLC chip coupled with fiber array was established to study the effects of temperature on insertion loss. The simulation results match experimental results, indicating that misalignment of PLC chip and fiber array is the main reason for insertion loss change. It is significant to consider the influences of global temperature rather than only paying attention to performance at static temperature when we evaluate the reliability of PLC optical splitters.

Objectives: In this paper a 1x4 optical beam splitter with a power splitting ratio of 80:20, based on 2D photonic crystal has been modeled for TE-polarized light. Methods: Designing of prototypes was done on the OptiFDTD software. Further, the simulations were performed and post-simulation the results were analyzed, this included the transmission spectra of the design which showed that the power was divided in a ratio of 80:20 that is 80 % and 20% of the transmitted signal. Also, the photonic band gaps were calculated using the Plane Wave Expansion (PWE) band solver. Findings: This prototype comprises of 2D Hexagonal lattice where the elliptical Si-rods are lined up in the air. The size of the wafer used for designing the prototype was taken to be 21µm*15µm.This particular design is a H-shaped splitter Finite Difference Time Domain (FDTD) and Plane Wave Expansion (PWE) methods are the mostly used mathematical analysis methods that are used for analyzing and calculating the band gap configuration and calculating the Photonic Band Gap of the photonic crystals. The Plane Wave Expansion method calculates the Eigen frequencies and dispersal characteristics of photonic crystals, with the help of Maxwell equations in frequency domain. The output power at output 1 and 3 was 80% and at the output 2 and 4 was calculated to be 20% of the transmitted signal. With the tolerance as 0.001, three band gaps were calculated and the values of their ban gaps were found to be 0.235179, 341851; 0.459574, 0.575928; 0.616383, 0.628378. Novelty/Improvement: This structure is designed in 1x4 dimensions, further the structure can be designed in various dimensions like 1x8, 1x16, 1x32 etc., depending on different applications. Keywords: Optical Splitter, Photonic Crystals, FDTD Simulation, PWE Band Solver

The joint exploitation of Radio over Fiber (RoF) and Time Modulated Arrays (TMA) is proposed, showing how, particularly within In-Building scenarios, it allows to combine the pervasiveness of the first technique with the beam-steering capability of the second. A cost-effective 3-element RoF-TMA system is presented and investigated, to realize a solution for small offices / private houses (SoHos). It is confirmed that bringing the feed to the antennas through the RoF system keeps the possibility for the TMA to radiate power at different frequencies, in each case with a steerable maximum direction. Referring to mobile signals with RF carriers of few GHz, it is shown that to guarantee, for each of the multiple beams emitted by the TMA, a maximum deviation of 5 from its ideal direction, it is sufficient that among the output branches of the 1:3 optical splitter utilized the length difference is maintained in the range of a few millimeters.

Silica-based planar lightwave circuit (PLC) devices can offer great potential for quantum key distribution (QKD) with the benefits of low-loss, low-cost, large-scale integration, miniaturization, stability and mass production. A quantum decoding integrated chip for QKD based on silica PLC technology was demonstrated, which consists of a variable optical splitter (VOS), an asymmetric Mach–Zehnder interferometer (AMZI) with a thermo-optic phase modulator (TOPM) and a delay line (DL) whose delay time is 400ps, and a variable directional coupler (VDC). The balanced pulsepairs of double channels with measured delay times of 396ps and 398ps respectively were obtained in the conditions of both classical optics and single-photon transmissions. The chip has advantageous to achieve high interference visibilities of double channels simultaneously for BB84 phase and time-bin protocols.

Most of the commercial Mach-Zehnder modulators (MZM) have extinction ratio below 30dB. At maximum transmission bias point, the MZM output contains only even-order optical sidebands along with carrier band, if extinction ratio is very high. However, in practice output also contains spurious odd-order optical sidebands. In this paper, we propose a system for suppressing spurious odd-order optical sidebands in an MZM at maximum transmission bias point. The system is employed using parallel MZMs, electrical phase shifters, optical splitter and optical combiner. The proposed system realizes an MZM with ultrahigh extinction ratio at maximum transmission bias point. The performance of proposed system is better than that of an MZM with extinction ratio of 30dB even at an offset of about ±10° in phase shifters.

We demonstrate $40\ \mu\mathrm{m}$ spatial resolution over a few kilometres by optical frequency domain reflectometry (OFDR). The measurement setup overcomes short distance measurement drawback and interrogates distant locations with high resolution. Application of an optical splitter in long-range high-resolution reflectometry is also investigated.

Nowadays, multimedia technology has led to broadband services such as the delivery of data, voice, and video or multiple-play services. PONs (Passive Optical Networks) gives these services worthwhile. Fiber to The Home (FTTH) with Gigabit-capable PON, is generally based on tree network topologies that use passive optical splitters. Splitting level for passive optical splitter can be employed in one or two levels in Optical Distribution Networks (ODNs) with the configuration of passive splitter 1:2, 1:4, 1:8, 1:16, 1:32, and 1:64. This paper discusses FTTH deployment using a high splitting ratio method by utilizing 1:8 passive splitters in each of the two levels in ODNs for residential areas. This high splitting ratio can increase the user capacity for the time ahead of user scaling. The proposed method is simulated by employing Optisystem software. The power link budget and bit error rate (BER) are considered as the G-PON eligibility standards in this paper. The received power and BER meet the eligibility standard set by ITU-T G.984.2, which is greater than −28 dBm, and not worse than 10-12 for broadband services, respectively. This method illustrates that the proposed configuration can be implemented in a rapid residential because every G-PON port can serve 64 users. It escalates 2560 users for every G-PON network, which is double the number of increasing users than the usual splitting method of 1: 4 and 1: 8.

Multimode interference (MMI)-based optical splitter is designed and experimentally demonstrated on silicon on insulator for on-chip optical interconnect. We have proposed MMI-based 1 × 2 optical 3-dB splitter having a compact footprint (2.8 × 27 μm2). The device shows low excess loss of 0.05 dB for TE mode at operating wavelength 1550 nm and

Realizing integrated optical interconnect systems requires optical waveguide components. A promising approach to manufacturing graded-index waveguide components is their embedding in thin glass sheets by ion-exchange processes. In this work, constraints imposed by the multivariate manufacturing process for the realization of single-mode input and output structures in multimode-interference-based (MMI-based) optical splitters are elaborated. Corresponding correlations between these constraints and the modeling of the devices are established with respect to not only the modeling of the manufacturing process but also the practical realization of these components.

The coupling of space light to optical fiber is the key problem in free space optical communication. The diameter of fiber core is very small, which brings great difficulty to coupling. We first analyze the coupling model, and propose the conical fiber array as a new receiver to improve the efficiency. After that, the sample of conical fiber array is produced in the laboratory, and the testing experiment in micro vibration environment is carried out. In this experiment, two methods are used to measure the received optical power. In the first method, the light from nine fibers is merged into one with the optical splitter. In the second method, a large target avalanche photodiode (APD) is used to receive the light from nine fibers. Compared with our previous work, both measurement methods show the coupling efficiency of the conical fiber array is higher.

The coupling of space light to optical fiber is the key problem in free space optical communication. The diameter of fiber core is very small, which brings great difficulty to coupling. We first analyze the coupling model, and propose the conical fiber array as a new receiver to improve the efficiency. After that, the sample of conical fiber array is produced in the laboratory, and the testing experiment in micro vibration environment is carried out, in which two methods are used to measure the received optical power. In the first method, a large target avalanche photodiode (APD) is used to receive the light from nine fibers. In the second method, the light from nine fibers is merged into one with the optical splitter. Both measurement methods show the sample meet the desired receiving requirements.

Micro-structured fibers are important devices that have drawn intensive attentions and proved to be powerful platforms for various applications over the past decades due to their remarkable merits and advantages, such as small footprint, immunity to electromagnetic interferences, light weight, high physical flexibility, and low cost. Modifications in optical fibers can be used as light-steering elements to excite and couple back different core and cladding modes and form various in-fiber structures, including in-line fiber interferometer, fiber micro-cantilever, fiber random gratings, and so on. These micro-structures, when applied as fiber-optic sensors in the presence of external disturbances, show high sensitivity in terms of the significant changes in the guided light features. Novel micro-structured bend-insensitive fiber-based in-line fiber interferometer and micro-cantilever have been proposed to realize both static and dynamic parameter measurements, including temperature, axial strain, surrounding refractive index, and vibration. We have also developed a novel fiber random grating along with a spectral correlation algorithm for simultaneous measurement of three static measurands. To move a step forward, random fiber lasers based on fiber random grating are achieved for either improving the laser performances or sensing applications of temperature, strain, and ultrasound measurements with high sensitivity.

We designed and fabricated a 100-GHz range integrated photoreceiver with zero-bias operational uni-traveling-carrier photodiode and pseudomorphic high electron mobility transistor amplifier, which performed the roles of photonic power generation and 100-GHz RF signal generation. Using the integrated photoreceiver, high data rate radio- and power-over-fiber transmission through multicore fiber communication was demonstrated. Subsequently, a bit error rate of $1\times 10^{- 3}$ could be achieved with 12 Gb/s, orthogonal frequency division multiplexing, 16 quadrature amplitude modulation, and an intermediate frequency of 92 GHz. The crosstalk issue in radio- and power-over-fiber transmission through multicore fiber was discussed.

In this paper, we present various designs of optical splitters for access networks, such as GPON and XG-PON by ITU-T with triple-play services (ie data, voice and video). The presented designs exhibit a step forward, compared to the solutions recommended by the ITU, in terms of performance in transmission systems using WDM. The quality of performance is represented by the bit error rate and the Q-factor. Besides the standard splitter design, we propose a new length-optimized splitter design with a smaller waveguide core, providing some reduction of non-uniformity of the power split between the output waveguides. The achieved splitting parameters are incorporated in the simulations of passive optical networks. For this purpose, the OptSim tool employing Time Domain Split Step method was used.

Low cost and low energy consumption are two important issues for the upgrade of next-generation passive optical network (PON). In this paper, we experimentally demonstrated a 40-Gb/s PON downstream transmission employing interleaved single carrier frequency-division multiplexing (I-SC-FDM) modulation and joint frequency-time domain equalization. At the transmitter, low peak-to-average power ratio and low-complexity signal is generated using simplified encoding structure of phase rotation and complex-to-real transform. At the receiver, the digital signal processing is of low computational complexity since very few taps of joint equalization are needed. 10G-class optics are used both in transmitter and receiver to maintain a low-cost system. Experimental results indicate that total 28.6 dB link power budget over 20 km transmission in C-band was successfully achieved without using any optical amplifier or optical dispersion compensation fiber, which supports up to $1:256$ optical splitter ratio in PON systems. The proposed scheme is of great reference significance in the next-generation PON systems.

Passive optical network (PON) is a popular technology, in recent days, which can be merged with peer-to-peer (P2P) network architecture. In P2P architecture, there is no need for a dedicated server and each peer can provide the data and receive the required data from other peers. With increasing traffic, there occurs a problem in resource sharing and therefore, the users experience higher latency and lower overall quality of services (QoSs). There are several recent studies regarding the use of PON in P2P network architecture, and some of them are studied for localization of traffic. But in the case of localizing traffic, the use of multiple upstream wavelengths was not studied previously. In this paper, we have proposed a new PON architecture and a new dynamic bandwidth allocation (DBA) algorithm called localizing traffic-based DBA (LT-DBA) to improve the overall QoSs of the PON-based P2P network. By localizing the intra-PON traffic, this architecture separates the inter-PON and intra-PON traffic. Here, in addition to the conventional passive optical splitter, a wavelength reflector is used which can reflect the upstream wavelength used for intra-PON traffic. We also propose an efficient management scheme of the intra-PON traffic, where no report is needed to send to the optical line terminal (OLT). The OLT needs not to allocate time-slot for local packets, and there is a huge optimization of resources. The LT-DBA scheme was evaluated by formulating mathematical models and numerical simulations. The simulations were performed by varying the percentage of local data and by changing the number of optical network units in PON. The simulation results show that our proposed architecture and LT-DBA scheme outperform the existing REDIRECT DBA scheme in terms of end-to-end delay, jitter, and throughput.

A 1 × 8 optical splitter on silicon-on-insulator technology is demonstrated with less than ±1.0 dB imbalance for a wavelength range of 300 nm, in which, a multimode interference (MMI) structure is introduced into an optical power splitter. A comparison is provided for 1 × 2 MMI splitters with and without tapers, a 1 × 2 MMI splitter with tapers is designed, fabricated and measured, which show a wider wavelength range of 300 nm with a lower imbalance of less than ±0.25 dB and a propagation loss of 3 dB.

A scintillator-based fast-ion loss detector (FILD) with a fast camera acquisition system has been installed on the Experimental Advanced Superconducting Tokamak (EAST), which can simultaneously measure the energy and pitch angle of the escaped fast ions in the scintillator plane. With the development of high-power external heating systems, the FILD system has been developed and upgraded with a photomultiplier tube (PMT) system to improve the temporal resolution to study fast-ion behaviors during neutral beam injection (NBI) heating and under resonant magnetic perturbation (RMP) discharge conditions. Photon imaging on the scintillator is divided into two parts by an optical splitter; one part is transferred to the fast charge-coupled device (CCD) system, and the other is transmitted to the PMT through an array of fibers. The FILD system is upgraded with a 25-channel (5 × 5) PMT (Hamamatsu Photonics, type no. H10492-003) array and a data acquisition system with a sampling rate of 2 MHz per channel. Preliminary experimental results show that the magnetic resonance perturbation affects the fast-ion losses. This paper presents the extended PMT acquisition system and the initial results of the FILD diagnostic relating to prompt losses, and the beam ion losses due to RMP are discussed.

We demonstrate a 500-MHz repetition rate, self-starting Yb:fiber laser incorporated with a phase biased nonlinear amplifying loop mirror as an artificial saturable absorber. The laser has two output ports; the beam splitter port delivers pulses, which can be compressed to 84.4 fs at an average power of 51 mW and the polarization beam splitter port directly output 61-fs pulses at an average power of 197 mW. Although the fiber is non-polarization maintaining, the mode locking is environmentally stable.

A novel variable optical delay line based on a hollow-core photonic bandgap fiber is proposed. The device incorporates microfluid, the end surface of which serves as an optical reflector, in the hollow-core of the fiber. The position of the fluid end is controlled by a syringe pump to change the optical delay of the reflected beam. We demonstrate wide tunability of the optical delay up to 1 m with a scan speed of several mm/s. The return loss and beat pattern in the reflected signal is studied and the potential of the device as an ultra-long delay line is discussed.

Optical splitter modules have been prepared based on 1x8 single mode silica planar waveguide optical splitter chips with 250 µm spacing and v-groove fiber arrays for applications in fiber optic communications. We report the technology of precise optical coupling and packaging of the splitter modules and the measurements of the insertion loss (< 11 dB), uniformity (< 0.80 dB) and polarization dependence loss (PLD < 0.10 dB) as well as the lateral profile and the image of the input and output lights for the wavelengths of 1310 nm and 1550 nm. The main characteristics of the prepared splitter modules are about the same for the commercial available products. The prepared modules have been tested for operation in the conditions of wide temperature range (5–80°C) and humidity range (50–98%) and no changes in the main characteristics were observed.

In this paper, we propose a flexible scheme to generate millimeter-waves (MMWs) for millimeter-wave radio-over-fiber (MMW-RoF) system. The proposed scheme has two configurations to adapt to various transmission bit rate by slightly rearranging the allocation of the system. The main structure of the system is cascaded LiNbO3 Mach-Zehnder modulators (LiNbO3-MZMs). The first configuration is cost effective method, where we utilize a wavelength division multiplexing de-multiplexer (WDM Demux) and an optical splitter (OS) to generate two unmodulated optical signals and a modulated optical signal. Each unmodulated optical signal and the modulated signal will form an optical single sideband (OSSB) modulation and therefore we simultaneously achieve a Q-band (45 GHz) and a V-band (60 GHz) MMWs in the receiver. The bit-error-ratio (BER) curves show that the power penalties of 45 GHz and 60 GHz are 0.6 dB and 1.1 dB at a BER of 1 × 10−9 with 2.5 Gb/s transmission data rate and 50 km fiber transmission distances. The second configuration can accommodate high bit rate, where few optical devices is rearranged to only generate a 60 GHz MMW with 40 Gb/s 4 quadrature amplitude modulation orthogonal frequency division multiplexing (4-QAM OFDM) signals. The power penalty is 1.1 dB at a BER of 1 × 10−9 with 50 km fiber transmission distances. Therefore, the proposed scheme can flexibly generate either two Q&V-band MMWs (45 GHz and 60 GHz) for the applications of the low data-rate transmission systems or one V-band MMW (60 GHz) for the applications of the high data-rate transmission systems.

We report on the design, fabrication and optical properties of large core multimode optical polymer splitter fabricated using fill up core polymer in substrate that was made by 3D printing technology. The splitter was designed by the beam propagation method intended for assembling large core waveguide fibers with 735 μ m diameter. Waveguide core layers were made of optically clear liquid adhesive, and Veroclear polymer was used as substrate and cover layers. Measurement of optical losses proved that the insertion optical loss was lower than 6.8 dB in the visible spectrum.

Optical amplification, which is necessary for extending the distance of fiber-optic time transfer, has significant impacts on the time transfer performance. In this paper, we investigate and optimize the optical amplification for the time transfer based on bidirectional time division multiplexing transmission over a single fiber with the same wavelength (BTDM-SFSW). Three optical amplification schemes, namely single fiber bidirectional amplifier (SFBA), single fiber bidirectional amplifier with magneto-optical switch (SFBA-MOS), and single-fiber bidirectional-transmission unidirectional optical amplifier (SFBT-UOA) are considered. For each optical amplification scheme over different fiber links, the timing jitter and uncertainty of time transfer are theoretically and experimentally analyzed. A simple timing jitter optimization method for the BTDM-SFSW links is proposed. Further evaluations are performed from the point of view of system complexity, operation cost, and compatibility with telecom optical networks. Results show that SFBA is more suitable over shorter fiber links for its lower complexity and cost, while SFBA-MOS or SFBT-UOA should be employed for longer fiber links to achieve the accepted time transfer performance.

In this paper, a triangular two-dimensional photonic crystal (PhC) of As2Se3-chalcogenide rods in air is presented and its photonic band diagram is calculated by plane wave method. In this structure, an optical waveguide is obtained by creating a line defect (eliminating rods) in diagonal direction of PhC. Numerical simulations based on finite difference time domain method show that when self-collimated beams undergo total internal reflection at the PhC-air interface, a total reflection of 90° occurs for the output beams. We also demonstrate that by decreasing the radius of As2Se3-chalcogenide instead of eliminating a diagonal line, a two-channel optical splitter will be designed. In this case, incoming self-collimated beams can be divided into the reflected and transmitted beams with arbitrary power ratio by adjusting the value of their radii. Based on these results, we propose a four-channel optical splitter using four line defects. The power ratio among output channels can be controlled systematically by varying the radius of rods in the line defects. We also demonstrate that by launching two optical sources with the same intensity and 90° phase difference from both perpendicular faces of the PhC, two logic OR and XOR gates will be achieved at the output channels. These optical devices have some applications in photonic integrated circuits for controlling and steering (managing) the light as desired.

A 1 × 2 optical polymer waveguide splitter of dynamic power tuning capability with low excess loss and high tuning resolution is presented. The device was developed based on angular misalignment technique of plastic optical fiber (POF) by allowing predetermined power to split out asymmetrically to two output ports. Non-sequential ray-tracing simulation and mathematical expression of the waveguide outputs matched well to the measured data. Excess loss of the dynamically tunable power-splitter maintains in the range of 0.58–1.85 dB, while the measured splitting-ratio resolution between adjacent power-tuning points is ±0.5% for both output ports. This dynamic power-tuning device would lead to some practical applications such as monitoring, power-controlling applications and sensor.

A kind of multi channel dual-core photonic crystal fiber polarization beam splitter is designed. We analyze the effects of the lattice parameters and the thickness of gold layer on the beam splitting by the finite element method. Numerical results show that the thickness of metal layer and the size of the air holes near the fiber cores are closely linked with the nature of the polarization beam splitter. We also obtain that extinction ratio can reach −73.87 dB at 1 . 55 μ m wavelength and at 1 . 41 μ m, 1 . 65 μ m extinction ratio can reach 30.8978 dB and 31.1741 dB, respectively. The comparison of the effect on the characteristic of the photonic crystal fiber with coating no gold is also taken into account.

Multicore and microstructured fibers open a new door for designing all-fiber telecom components. In this article we propose a design of an optical power splitter based on the phenomenon of power coupling in the tapered splice between a single-core (SMF-28) and a seven core fiber (MCF-7), which was originally developed for spatial division multiplexing telecommunication systems. Comprehensive numerical analysis is presented and backed up with an experimental demonstration.

This paper proposes a novel design of an integrated multi-arm power splitter based on photonic crystal waveguides. A 1 × 5 power splitter is proposed by introducing line defects to form a one input waveguide arm and five output waveguide arms. The plane wave expansion method (PWE) is used to investigate the dispersion characteristics of the light coupling between the guided modes in the photonic band gap (PBG) from 0.037 ω/2πc to 0.095 ω/2πc frequency range. Using Finite-Difference Time Domain (FDTD) method, we calculated the power splitting across each output arm; 52.2% in arm C, 16.9% in arm D, 14.6% in arm E, 12.1% in arm A and 3.4% in arm B. The total observed transmission efficiency of the splitter is 99.2%. Further, the time response of electric field along the Y direction (Ey) which is perpendicular to the X-Z plane is studied. The output arms C, E, D and B show beam shaped envelope response while the remaining output arm A exhibit negligible variation with time. The compact and low cost proposed design contributes to the state of art progress in the field of photonics integrated circuits (PICs) technology where the power splitter plays a prominent role of splitting optical power between all the optical elements integrated in the chip.

A novel concept of 1 × 16 power splitter based on a variable multicore photonic crystal fiber (PCF) structure is described. Numerical simulations showed how the optical signal can be split in a PCF structure having dimensions of 60 μm × 60 μm × 3.582 mm. The coupled mode analysis and beam propagation method (BPM) was used for analyzing the multicore PCF based 1 × 16 splitter. The input optical signal at a wavelength of 1.55 μm inserted into the central core was divided into sixteen output cores, each with a 6.25% of the total power. The full width half maximum (FWHM) bandwidth found for each core was 100 nm.

A design of polarization splitter with dual-core photonic crystal fiber (DC-PCF) has been proposed. By using a finite-element method, the incident polarized light can be split into two orthogonal single-polarization states (x-polarization and y-polarization) through the proposed polarization splitter. Numerical results show the bandwidths of the x-polarization and y-polarization modes are 100 nm and 55 nm at the wavelength of 1.5 μm. The length of the designed DC-PCF is 2 mm and the extinction ratios of the x-polarization and y-polarization modes are −52.5 dB and −32.85 dB at the wavelength of 1.5 μm, respectively. This study will be very helpful to design and manufacture a splitter based on DC-PCF for better performance.

This paper reviews novel distributional measurement technologies that were recently developed for monitoring the health of optical fibers in communication systems. The development of these technologies has an extensive history. Physical phenomena of optical fibers have been exploited, and several requirements in managing telecommunication systems have been considered. However, significant progress is still required for diagnosing fibers in long-haul and access networks. In addition, these technologies may stimulate the development of distributional fiber sensors.

The development of mode division multiplexing has found numerous interesting applications in optical sensing. A major challenge has been how to control the mode composition of the interrogation signals. In this work, we presented a time-domain method that can adaptively control the form of optical signals at multiple locations in a two-mode-fiber. We also carry out a preliminary study that suggests the method of adaptive mode control is compatible with the requirements of optical sensing.

The 53.125 Gbps transmission is experimentally investigated over a next-generation wideband multimode optical fiber (NG-WBMMF) using transmitter optical sub-assemblies (TOSAs) and wideband receiver optical sub-assemblies (ROSAs) developed for 25 Gbps short wavelength division multiplexing (SWDM) operation. A commercial 100 Gbps four-level pulse amplitude modulation integrated circuit (PAM4 IC) evaluation kit with real-time digital signal processing (DSP) is used. Dual wavelength transmission (2 λ × 53.125 Gbps) tests over 300 m of NG-WBMMF are carried out for the wavelength pairs 850, 880 nm and 910, 940 nm with a 4 × 1 optical MUX/DeMUX in the link. Measured pre-forward error correction (FEC) bit error ratio (BER) below the KP4 FEC threshold of 2.4 × 10–4 indicates the feasibility of 100/200 Gbps transmission over NG-WBMMF using a PAM4 chipset with real-time DSP. Single wavelength transmission (1 λ × 53.125 Gbps) using long wavelength TOSAs at 976 and 1066 nm is also studied. Pre-FEC BER below 2.4 × 10–4 is achieved over 300 m at 976 nm and 200 m at 1066 nm. Single wavelength tests from 850 to 940 nm had the same results as the 976 nm wavelength. Thus, this is the first experiment which shows the potential of 400 Gbps transmission with eight SWDM wavelength windows over a single NG-WBMMF using SWDM TOSAs, ROSAs, and commercial 100 Gbps PAM4 chipset.

Fiber optics is an important part in the telecommunication infrastructure. Large bandwidth and low attenuation are features for the fiber optics to provide gigabit transmission. Nowadays, fiber optics are used widely in long distance communication and networking to provide the required information traffic for multimedia applications. In this paper, the optical fiber structure and the operation mechanism for multimode and single modes are analyzed. The design parameters such as core radius, numerical aperture, attenuation, dispersion and information capacity for step index and graded index fibers are studied, calculated and compared for different light sources.

We systematically measure the noise properties of wide-band optical comb lightwave out of a dispersion-engineered nonlinear fiber mixer, which has restricted the use of such comb technology in the pilot-tone-aided coherent transmission over multi-core fibers. We compare the performance of three transmission technologies using different carrier sources, a 11.7-km multi-core fiber link and 10-GBaud 64 QAM signal. Superiority of shared carrier reception methods against self-homodyne detection is experimentally observed when the noisy optical comb is used as the carrier source. Modified shared carrier reception potentially provides further advantage when we employ higher order QAM formats.

The paper deals with fiber-optical cable winding methods for realization of fiber-optic communication line with high-speed object. We consider possible options of coils for optical cable winding providing mobility of one of the cable ends on an object. It is shown that the choice of a winding process is caused by the need of ensuring the minimum deformation of fiber-optical micro cable in case of separation from a winding body. It is revealed that the minimum tension value and its unevenness are observed when reeling from coils with a rocket form. Design ratios for determination of winding parameters are given. It is shown that reduction of tension unevenness reduces the jumps of internal tension and probability of break and emergence of optical signal local attenuation. Decrease in internal stresses occurs due to the absence of overlapping of the coils of the underlying layers with the overlying ones. To confirm the operability and the possibility of constructive implementation of the selected winding scheme, experiments were carried out to perform rocket and other types of winding with the use of a specially designed machine model. It is shown that the application of line rocket winding enables to achieve stability when reeling a cable during the movement and excludes breaks. Attenuation of optical signal decreases due to the increase in the bend minimum radius. This phenomenon is explained by reduction of the internal stresses causing optical signal attenuation in the place of cable separation from the coil.

We present a monitoring technique that can be directly integrated in the sub-carrier multiplexing (SCM) transceiver for PtP and wavelength division multiplexing and sub-carrier multiplexing passive optical networks applications. The technique is based on the detection of the backscattered signal from a baseband tone (100 Hz to 100 kHz) and interpretation with the least absolute shrinkage and selection operator (LASSO) operator, a signal processing technique which identifies the fault positions based on the mathematical model of the received signal. The proposed single-ended fiber probing method enables the location of multiple faults with no a-priori knowledge of the fiber, and offers low-cost in-service operation with negligible impact on data transmission, few meters spatial resolution, and limited dynamic range. Due to all its advantages, but also considering its reach limitation, the SincLASSO method features as an ideal monitoring candidate for short reach sub-carrier multiplexed optical fiber networks, such as the ones intended for analog mobile Fronthaul based on fiber and fiber-extended copper lines.

In this paper, we propose a novel tunable power splitter based on symmetric Mach-Zehnder (MZ) structure to achieve the polarization-insensitive and broadband performance. This good performance is realized by utilizing two 3 dB broadband directional couplers and square waveguides in a conventional symmetric MZ structure. Based on thermo-optic effect, the power splitting ratio of our power splitter for the TE and TM modes can be equally controlled in a wide operating bandwidth of 63 nm. Our results show a low polarization-dependent loss of 0.001-0.089 dB over a wide wavelength range of 1541-1604 nm.