Design of a 1 × 2 novel optical switch based on polarization converters and splitters

In this paper, a 1?×?2 optical switch based on two TE/TM polarization converters, one 1?×?2-polarization beam splitter and a hybrid 2?×?2-polarization beam splitter/combiner is designed and discussed. The novelty of this work resides in the design of a 2?×?2-hybrid polarization beam combiner/splitter, operating as a 2?×?2 polarization optical switch through the combining and the splitting of polarized signals issued from two TE/TM polarization controllers. The novel hybrid splitter/combiner can route an optical signal either to a bar or a cross port with an extinction ratio higher than 90 dB, thanks to the feature of polarization splitting used in this device to suppress undesired polarization states and minimize the polarization-dependent loss. We have used polarization beam converters to switch between two orthogonal modes in order to facilitate the routing of these signals through the 2?×?2-hybrid polarization splitter/combiner. We changed the polarization states of signals, in our simulation via OptiSystem, through polarization controllers, by modifying only their phase shifts between 0 rad and π rad. The proposed 1?×?2 optical switch presents an average insertion loss of 3.5 dB.

     

A 2×2 SOI mach-zehnder thermo-optical switch based on strongly guided paired multimode interference couplers

A silicon-on-insulator 2×2 Mach-Zehnder thermo-optical switch is developed based on strongly guided paired multimode interference couplers. The multimode-interference couplers were etched deeply for improving coupler characteristics such as self-imaging quality, uniformity and fabrication tolerance. The proposed switch achieves good performances, including a low insertion loss of -11 .OdB, a fiber-waveguide coupling loss of -4.3dB and a fast response speed measured to be 3.5 and 8.8 μs for raise and fall switching time, respectively.     

A 2×2 SOI mach-zehnder thermo-optical switch based on strongly guided paired multimode interference couplers

A silicon-on-insulator 2×2 Mach-Zehnder thermo-optical switch is developed based on strongly guided paired multi-mode interference couplers. The multimode-interference couplers were etched deeply for improving coupler characteristicssuch as self-imaging quality, uniformity and fabrication tolerance. The proposed switch achieves good performances,including a low insertion loss of –11.0dB, a fiber-waveguide coupling loss of –4.3dB and a fast response speed measuredto be 3.5 and 8.8 μs for raise and fall switching time, respectively.     

A tunable Mach–Zehnder interferometer based on dual micro-cavity photonic crystal fiber for load measurement

Photonic Network Communications - Optical fiber technologies are widely engaged in variety of industries, machines and production lines due to their precise results and low cost. Optical sensors...     

A 128 × 128 pixel ultraviolet photodetector based on a diamond sensor

A new 128 × 128 pixel matrix photodetector with a semiconductor diamond sensor is designed, fabricated, and studied. A 128 × 128 pixel ultraviolet image is detected experimentally.     

Characteristics of bend sensor based on two-notch Mach–Zehnder fiber interferometer

A compact all-fiber modal Mach–Zehnder interferometer is presented based on two notches at different locations along normal single-mode fibers by CO₂ laser irradiation. Two notches are mode splitter and mode combiner, respectively. This configuration which does not need any troublesome cleaving or aligning process is demonstrated as a bending sensor. The results suggest that the transmission loss varies and the interference fringe shifts with the bending increasing. The fluctuation of temperature dose not affects the shape of the interferometer fringe and transmission. Therefore, the proposed device offers salient advantages of simple fabrication technique and low cost. In addition, a high stability over time was expected since the irradiated notches do not degrade over time or with temperature. Due to its asymmetry, it also possesses higher sensitivity to orientation, which would be a promising unit for sensor applications.     

A novel 2.2 Gbps LVDS driver circuit design based on 0.35μm CMOS

This paper presents a novel high-speed low voltage differential signaling(LVDS) driver design for point-to -point communication.The switching noise of the driver was greatly suppressed by adding a charge/discharge circuit and the operating frequency of the circuit was also increased.A simple and effective common-mode feedback circuit was added to stabilize the output common-mode voltage.The proposed driver was implemented in a standard 0.35μm CMOS process with a die area of 0.15 mm~2.The test result show...     

A novel Sigma–Delta based parallel analogue-to-residue converter

An important step in the residue number system (RNS) based signal processing is the conversion of signal into residue domain. Many implementations of this conversion have been proposed for various goals, and one of the implementations is by a direct conversion from an analogue input. A novel approach for analogue-to-residue conversion is proposed in this research using the most popular Sigma–Delta analogue-to-digital converter (SD-ADC). In this approach, the front end is the same as in traditional SD-ADC that uses Sigma–Delta (ΣΔ) modulator with appropriate dynamic range, but the filtering is done by a filter implemented using RNS arithmetic. Hence, the natural output of the filter is an RNS representation of the input signal. The resolution, conversion speed, hardware complexity and cost of implementation of the proposed ΣΔ based analogue-to-residue converter are compared with the existing analogue-to-residue converters based on Nyquist rate ADCs.     

Strain-insensitive and high temperature fiber sensor based on a Mach–Zehnder modal interferometer

In this paper, a strain insensitive high temperature fiber sensor based on the modal interferometer is proposed. It is composed of a piece of small-core photosensitive fiber (SCPSF) which is spliced between two pieces of single mode fiber (SMF). Compared to other high temperature fiber sensor based on the modal interferometer, the sensor owns the highest temperature sensitivity of 106.64 pm/°C from 200 °C to 1000 °C. The temperature to strain cross sensitivity of the sensor is low and only 0.00675 °C/με. The reasons for realizing the high temperature sensitivity is also discussed.     

Ring cavity fiber laser based on Fabry-Pérot interferometer for high-sensitive micro-displacement sensing

A ring cavity fiber laser based on Fabry-Pérot interferometer (FPI) is proposed and demonstrated experimentally for micro-displacement sensing. Simulation results show that the dips of the FPI transmission spectrum are sensitive to the cavity length of the FPI. With this characteristic, the relationship between wavelength shift and cavity length change can be established by means of the FPI with two aligned fiber end tips. The maximum sensitivity of 39.6 nm/μm is achieved experimentally, which is approximately 25 times higher than those in previous reports. The corresponding ring cavity fiber laser with the sensitivity for displacement measurement of about 6 nm/μm is implemented by applying the FPI as the filter. The proposed fiber laser has the advantages of simple structure, low cost and high sensitivity.     

QSM-IDM – A novel quadrature spatial modulation based on interleaving division multiplexing for multiple antenna system

Quadrature Spatial Modulation (QSM) is a high spectral efficiency Multiple-Input Multiple Output (MIMO) technique used to improve the spectral efficiency of wireless communication systems. The main concept of QSM is to extend the spatial constellation of the conventional Spatial Modulation (SM) in both the in-phase and quadrature components of the data symbol. In this paper, because QSM-based on Interleaving Division Multiplexing (IDM) has not been introduced in the literature as a multiple antenna system, we introduced a novel scheme, called QSM system based on Interleaving Division Multiplexing (QSM-IDM). The antenna sets are also applied to a spreader, before being used to assign an antenna number for information transmission. Analysis and simulations for a flat fading channel show that the proposed QSM-IDM method significantly outperforms the original QSM system with the same data rate, while maintaining a relatively acceptable complexity. The obtained simulation results show that the conducted analysis yields significant improvements for the accuracy of the proposed scheme, with satisfactory complexity.     

A novel scheme to suppress the third-order intermodulation distortion based on dual-parallel Mach–Zehnder modulator

A scheme to enlarge the spurious free dynamic range (SFDR) of the microwave photonic link is proposed based on a dual-parallel Mach–Zehnder modulator (DPMZM). By properly adjusting the phase of the RF signals and the bias voltages of the DPMZM, the second-order spurious components in the optical carrier band (OCB) of the two sub-MZMs can be canceled out completely, and the third-order and fifth-order spurious components in the first-order upper sideband (1-USB) produced by one sub-MZM have equal amplitude but \(180{^{\circ }}\) phase difference with the other sub-MZM. Therefore, as the two optical beams are combined at the output of the DPMZM and the OCB and the 1-USB are abstracted by a bandpass filter to generate the transmitted signal, all the major optical spurious components that contribute to the third-order intermodulation distortion (IMD3) are canceled out. Theoretical analysis and simulation results show that the proposed scheme, without digital linearization and other optical processor, can suppress IMD3 approximately 30 dB and improve the SFDR by \(18~\hbox {dB}\,\hbox {Hz}^{2/3}\) compared with the conventional quadrature biased MZM system.     

Dual and tri-band bandpass filters based on novel Π-shaped resonator

A novel Π-shaped resonator is proposed, and compact dual-band and tri-band bandpass filters that meet IEEE 802.11 application requirements by using the new resonator are designed. The dual-band bandpass filter centres at 2.45 and 5.6 GHz with a simulated passband insertion loss of no more than 0.8 dB, and the tri-band bandpass filter which is got by two-path coupling achieves simulated passband insertion loss of no more than 1.1 dB. The new designs are demonstrated by experiment. The new filters have advantages of simple and compact structures, low passband insertion losses, good frequency selectivity and miniature circuit sizes. All these have prospect to be applied in future wireless communication systems.     

Digital demodulation technique for fiber-optic hydrophones based on 3×3 couplers

In this paper,a digitized real-time demodulation system for optical hydrophones based on a 3×3 coupler is proposed.The system is built as a virtual instrument via the dynamic data acquisition platform from NI company.Compared with the commonly used systems composed of analogue circuits,the proposed system has better accuracy and is more flexible in applications.The error analysis of the proposed system is also given.