P. P. Yupapin

All-Optical OFDM Generation for IEEE802.11a Based on Soliton Carriers Using Microring Resonators

The optical carrier generation is the basic building block to implement all-optical orthogonal frequency-division multiplexing (OFDM) transmission. One method to optically generate single and multicarriers is to use the microring resonator (MRR). The MRRs can be used as filter devices, where generation of high-frequency (GHz) soliton signals as single and multicarriers can be performed using suitable system parameters. Here, the optical soliton in a nonlinear fiber MRR system is analyzed, using a modified add/drop system known as a Panda ring resonator connected to an add/drop system. In order to set up a transmission system, i.e., IEEE802.11a, first, 64 uniform optical carriers were generated and separated by a splitter and modulated; afterward, the spectra of the modulated optical subcarriers are overlapped, which results one optical OFDM channel band. The quadrature amplitude modulation (QAM) and 16-QAM are used for modulating the subcarriers. The generated OFDM signal is multiplexed with a single-carrier soliton and transmitted through the single-mode fiber (SMF). After photodetection, the radio frequency (RF) signal was propagated. On the receiver side, the RF signal was optically modulated and processed. The results show the generation of 64 multicarriers evenly spaced in the range from 54.09 to 55.01 GHz, where demodulation of these signals is performed, and the performance of the system is analyzed.

W-Band OFDM Transmission for Radio-Over-Fiber Link Using Solitonic Millimeter Wave Generated by MRR

A system comprises of a W-band (75-110 GHz) optical millimeter (mm)-wave generation using microring resonators (MRRs) and radio-over-fiber (RoF) link architectures is presented for multigigabit data rates demand. The MRRs are used to generate optical mm-wave soliton pulses for W-band applications. To achieve faster transmission speed wirelessly, higher spectral efficiency (SE) and better transmission performance, orthogonal frequency-division multiplexing (OFDM) is used. The results show that the MRRs support W-band optical soliton pulses, which can be used in an OFDM transmission/receiver system. Localized narrow bandwidth soliton pulses within frequencies of 92.2-93.2 GHz can be seen in the throughput port of the Panda system with respect to the full width at half maximum and free spectrum range of 3.5 and 184 MHz, respectively. The error vector magnitude of the system was measured and the viability of the solitonic OFDM-based system for RoF link over 25-Km fiber link and 2-m wireless link was confirmed. The data rate of the system with 16-quadrature amplitude modulation is measured as 43.6 Gb/s and with 10 GHz of bandwidth, the SE is obtained as 4.36 bit/s/Hz.

Growth of small diameter multi-walled carbon nanotubes by arc discharge process

Multi-walled carbon nanotubes (MWCNTs) are grown by arc discharge method in a controlled methane environment. The arc discharge is produced between two graphite electrodes at the ambient pressures of 100 torr, 300 torr, and 500 torr. Arc plasma parameters such as temperature and density are estimated to investigate the influences of the ambient pressure and the contributions of the ambient pressure to the growth and the structure of the nanotubes. The plasma temperature and density are observed to increase with the increase in the methane ambient pressure. The samples of MWCNT synthesized at different ambient pressures are analyzed using transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. An increase in the growth of MWCNT and a decrease in the inner tube diameter are observed with the increase in the methane ambient pressure.

Multiwalled carbon nanotube synthesis using arc discharge with hydrocarbon as feedstock

Synthesis of multiwalled carbon nanotube (MWCNT) by arc discharge process is investigated with methane (CH4) as background and feedstock gas. The arc discharge is carried out between two graphite electrodes for ambient pressures 100, 300, and 500 torr and arc currents 50, 70, and 90 A. Plasma kinetics such as the density and temperature for arc discharge carbon plasma is determined to find out the contribution of physical parameters as arc current and ambient pressure on the plasma dynamics and growth of MWCNT. With increase in applied arc current and ambient pressure, an increase in plasma temperature and density is observed. The synthesized samples of MWCNT at different experimental conditions are characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. A decrease in the diameter and improvement in structure quality and growth of MWCNTare observed with increase in CH4 ambient pressure and arc current. For CH4 ambient pressure 500 torr and arc current 90 A, the well-aligned and straight MWCNT along with graphene stakes are detected.

Molecular Filter On-Chip Design

This paper presents the use of a modified add-drop optical filter known as a PANDA microing resonator which can be designed on a chip. By using an optical tweezer, the required molecules can be trapped and moved to the required destinations, where finally, the required molecules can be retrieved (filtered) by using the tunable filter via the add-drop filter control. In application, storage molecules in the bottle in the designed chip can be trapped and moved to the required targets by optical tweezers, which can transport via the optical waveguide. Therefore, this technique can be used to form the molecular filter. This is a new technique and important for drug delivery, drug targeting and molecular electronics, which is described, the optical tweezer generation using a PANDA ring resonator is also reviewed. Results obtained have shown that the multivariable filter can be obtained by tunable trapping control. the simulation results are obtained by using the commercial MATLAB software, which is found that this device can be used to form the hybrid electronic device, in which the combination between the conventional electronics and molecular electronics can be established, moreover, the multivariable molecular filter can be formed, which can be available for high capacity molecular communication and networks.

Drug Delivery System Model using Optical Tweezer Spin Control

A new concept of molecular motor using optical tweezers within a modified optical add–drop filter known as PANDA ring resonator is proposed. In simulation, dark and bright solitons are input into the system. The orthogonal tweezers can be formed within the system and detected simultaneously at the output ports. Under the resonant condition, the optical tweezers generated by dark and bright soliton pair corresponding to the left-hand and right-hand rotating solitons (tweezers) can be generated. In application, the trapped molecules can be moved and rotated to the required destinations, which can be useful for healthcare applications, especially, in drug delivery, medical diagnosis and therapy.

Fast, Slow, Stopping and Storing Light Simultaneously using a PANDA Ring On-Chip

Past and slow light behaviors are the interesting aspects of light which can be useful for many fundamental and applied researches. Pornsuwancharoen and Yupapin et al. [1] have proposed the use of a simple device called “microring resonator” to perform such behaviors. In this research work, the four different behaviors of light i.e., fast, slow, stopping and storing of light where investigated using a ring resonator. Nowadays, stopping or cooling light beam has become the promising technique for atom/molecule trapping investigations (using static or dynamic tweezers), especially, after the announcement of Nobel Prize 2012 in Physics on the whispering gallery modes [2, 3]. There are two more kinds of devices that can be used to trap light beams, the use of microcavity arrays performed by Yanik and Fan [4], and nonlinear microring resonator by Yupapin and Pornsuwancharoen [5] for stopping light (laser beam). Nanyang Technological University scientists have also done experiment to slowing the light in microresonators using a microring system recently [6]. This concept is a concrete backbone for many applications.

SOLITON SPIN AND WAVE-PARTICLE DUALITY

By using the optical add-drop filter which is formed by a microring resonator, and after a dark soliton pulse is fed into an input port of the add-drop filter, the orthogonal soliton pair (dark and bright solitons) can be formed within the system and detected simultaneously at the output ports. Under the resonant condition, the conversion of dark and bright solitons corresponding to the left-hand and right-hand soliton orientations can be generated and seen. Whenever a soliton (photon) is absorbed by an object, an angular momentum of either +ℏ or -ℏ is imparted to the object, in which two possible soliton states known as soliton spins are exhibited and confirmed by the helical phase presentation. In application, the train of orthogonal solitons, i.e. many solitons (photons) with slightly different wavelengths can be generated by using the modified add-drop filter, which is available for many soliton spins and long distance spin transport investigations.

A comprehensive treatment of parametric effect in a silicon microring resonator

Silicon microring resonator provides a new platform to form the building block for all-optical circuits, where it could be integrated on a single chip as a passive or active components. Here, we report a comprehensive treatment of parametric effect in a symmetrical add/drop silicon microring resonator with 5 μm radius operating within telecom wavelength spectrum or C-band ranging from 1530 nm to 1565 nm. The power outputs of the system are analyzed by using transfer matrix method. The FSR and FWHM have been optimized. The results demonstrated here will pave the way towards the new on-chip and chip-to-chip architecture and structure for low power and high bandwidth applications especially for all-optical switch and optical modulator.

Soliton pulse induces TPA effect in a silicon MRR all-optical switch

One of the critical problems in achieving a real practical all-optical switching devices is the requirement for a strong material nonlinearity. A strong material nonlinearity is crucial in order to achieve a low switching power. However, silicon-based all-optical switches require extremely high switching power due to its relatively weak nonlinear optical properties. To overcome this limitation, we have designed an all-optical switch configuration based on silicon microring resonator structure and demonstrated the switching operation based on the nonlinear effects induced by a soliton pulse. The soliton pulse induces free-carrier concentration through two-photon absorption (TPA) effect and this leads to enhance the refractive index change and enhance the nonlinearity of the silicon. Thus, the silicon microring resonator alters the nonlinear phase shift which is required for switching.