Low Crosstalk Values Research Articles

Optimization of the interlayer distance for low-loss and low-crosstalk double-layer polymer optical waveguides.

The interlayer distance optimized for low-loss and low-crosstalk double-layer polymer optical waveguides was investigated to enhance their transmission performance. Simulations were conducted to determine the minimal interlayer distances for double-layer optical waveguides with different core sizes. An optimal interlayer distance of 24 µm was identified for a 20 µm × 20 µm double-layer waveguide, which ensured interlayer crosstalk below -30 dB when roughness remained under 80 nm. The double-layer waveguides were fabricated employing ultraviolet lithography combined with the overlay alignment method. Based on experimental optimization, the important fabrication parameters were optimized, such as a plasma treatment time of 10 s, a core exposure dose of 500 mJ/cm2, and a cladding exposure dose of 240 mJ/cm2. Additionally, the fabricated double-layer waveguides, with an interlayer distance of 24.5 µm, exhibited low transmission losses of less than 0.25 dB/cm at 850 nm and 0.40 dB/cm at 1310 nm, respectively. The low interlayer crosstalk values were less than -52 dB at 850 nm and -60 dB at 1310 nm, respectively. The agreement between the experimental results and the simulation findings indicates that this method offers a promising approach for fabricating double-layer waveguides with good performances.

Ultrawide-bandwidth on-chip spectrometer design using band-pass filters

Here, we present the design and simulation of an ultrawide-bandwidth on-chip spectrometer that can be used in various applications, e.g. spectral tissue sensing. It covers 1200 nm wavelength range (400 nm-1600 nm) with 2 nm spectral resolution. The overall design size is only 3 × 3 cm2. The ultra-wide spectral range is made possible by using novel on-chip band-pass filters for the coarse wavelength division. The fine resolution is provided by the arrayed waveguide gratings. The band-pass filter is formed by using bend waveguides and adiabatic full-couplers. The additional loss caused by the band-pass filter is relatively small. The proposed spectrometer covers entire 400 nm-1600 nm range continuously with low crosstalk values. We envision that this design can be used in several different applications including food safety, agriculture, industrial inspection, optical imaging, and biomedical research.

An Online Routing Algorithm for Space Division Multiplexing Based Elastic Optical Networks

We focus on the optimisation of lightpath routing in an online space division multiplexing-based elastic optical network (SDM-b-EON). We propose a new online routing algorithm, named as online routing algorithm (ORA), which accounts for the presence of the transceivers in the network, and also ensures the routing of the transparent lightpaths through the spectral super-channels over spatial multiple core fibres (MCFs) links. We conduct extensive simulations considering two realistic network topologies and two different MCF crosstalk values which result in different transmission reach values. The obtained results demonstrate that: 1) ORA significantly outperforms the various reference routing techniques in terms of the bandwidth blocking probability (BwBP); 2) in regard to the use of modulation formats, for low crosstalk values, the most used format is QPSK rather than BPSK which results in lesser traffic being accepted by the SDM-b-EON; 3) as the transceivers amount increases, more frequent demands blocking occurs owing to spectrum scarcity. Overall, our study shows that in a SDM-b-EON, larger amount of transceivers can be efficiently used in comparison to the less efficient spectrum usage, since the spectrum significantly experiences fragmentation owing to the spectrum-contiguity and spectrum-continuity constraints.

An online routing algorithm for space division multiplexing-based elastic optical networks

We focus on the optimisation of lightpath routing in an online space division multiplexing-based elastic optical network (SDM-b-EON). We propose a new online routing algorithm, named as online routing algorithm (ORA), which accounts for the presence of the transceivers in the network, and also ensures the routing of the transparent lightpaths through the spectral super-channels over spatial multiple core fibres (MCFs) links. We conduct extensive simulations considering two realistic network topologies and two different MCF crosstalk values which result in different transmission reach values. The obtained results demonstrate that: 1) ORA significantly outperforms the various reference routing techniques in terms of the bandwidth blocking probability (BwBP); 2) in regard to the use of modulation formats, for low crosstalk values, the most used format is QPSK rather than BPSK which results in lesser traffic being accepted by the SDM-b-EON; 3) as the transceivers amount increases, more frequent demands blocking occurs owing to spectrum scarcity. Overall, our study shows that in a SDM-b-EON, larger amount of transceivers can be efficiently used in comparison to the less efficient spectrum usage, since the spectrum significantly experiences fragmentation owing to the spectrum-contiguity and spectrum-continuity constraints.

16-Channels wavelength efficient demultiplexing around 1.31/1.55 μm in 2D photonic crystal slab

An original design of compact and efficient 16-channels demultiplexer integrated in a photonic crystals PhCs slab for dense wavelength demultiplexing near infrared application operating around two wavelengths 1.31 μm and 1.55 μm with an occupied area of 752.25 μm2 is proposed in this paper. The demultiplexer is based on a square lattice two-dimensional PhCs quasi square ring resonator (QSRR) for wavelength division multiplexing applications; it consists of two blocks where each one of theme is dedicated to function around one band of wavelengths 1.31 μm or 1.55 μm separated by a wideband demultiplexer. The demultiplexer is of good-quality factor Q that equals 517.6 for a spectral width of 3 nm and 622 for a spectral width 2.5 nm, low crosstalk values between -9 dB and-41 dB were observed in the same block. Furthermore, an extreme low crosstalk values between -27 dB and-288 dB were noted between two different blocks (1.31 μm and 1.55 μm), with high transmission efficiency of about 90%.

Silicon High-Order Mode (De)Multiplexer on Single Polarization

Mode-division multiplexing on an integrated photonic chip is critical for future optical networks. High-order mode multiplexing is desired to increase the transmission capacity. Here, we propose and experimentally demonstrate a silicon on-chip high-order mode (de)multiplexer using subwavelength grating (SWG) structure, which supports 11-mode (de)multiplexing on a TE-polarized light (TE0–TE10). The proposed mode (de)multiplexer comprises three directional couplers and seven SWG-based directional couplers. Measurement results show that all the 11 channels have low crosstalk values (−15.4 to −26.4 dB) and low insertion losses (0.1 to 2.6 dB) at 1545 nm. To the best of our knowledge, our device achieves the highest-order-mode (de)multiplexing on a silicon photonic chip.

Tunable High Performance 16-Channel Demultiplexer on 2D Photonic Crystal Ring Resonator Operating at Telecom Wavelengths

AbstractHere, we proposed a high performance 16-channel optical demultiplexer using two-dimensional photonic crystal ring resonator for telecommunication systems. By plane wave expansion (PWE) method the photonic band gap (PBG) of proposed structure calculated. Then, with finite difference time domain (FDTD) method the performance parameters of designed two-dimensional photonic crystal demultiplexer are analyzed. It is found that the channel wavelength of wavelength-division multiplexing (WDM) is truly tuned by changing the structure parameters of the demultiplexer and position of rod. Output peaks located in the optical communication C-band and L-band with the transmission efficiency of 99 %. The demultiplexer exhibits high-quality factor of 5176, and spectral width of 0.3. Very low crosstalk values are between −19 dB and −90 dB where, device only occupies an area of 1708.65 µm2. The proposed compact 16-channel demultiplexer can find more applications for the ultra-compact WDM systems in highly integrated telecommunication circuits.

Hybrid electro-optic plasmonic modulators based on directional coupler switches

By breaking the diffraction limit, plasmonics enable the miniaturization of integrated optical signal processing units in a platform compatible with traditional CMOS technology. In such architectures, modulators and switches are essential elements for fast and low-power optical signal processing. This work presents the design of a CMOS-compatible hybrid plasmonic modulator based on directional couplers enhanced with a layer of electro-optic polymer. The modulator shows very broad operating window with low crosstalk values and very small footprint with respect to similar couplers and switches of the silicon photonics platform.

Non-blocking 2 × 2 switching unit based on nested silicon microring resonators with high extinction ratios and low crosstalks

In this paper, we propose and demonstrate a 2 × 2 optical Benes switching unit based on two nested silicon microring resonators (MRRs) monolithically integrated on a silicon-on-insulator (SOI) wafer. High extinction ratios (ERs) of about 44.7/38.0 dB and low crosstalk values of about −37.5/−45.2 dB at cross/bar states are obtained with the fabricated device. The operation principle is theoretically studied and the switching function is verified by system demonstration experiments with 10 and 12.5 Gb/s non-return-to-zero (NRZ) signals. The switching speed on the order of gigahertz based on free carrier effect in silicon is also experimentally demonstrated.

Low cross-talk 2 × 2 silicon electro-optic switch matrix with a double-gate configuration

In this study, a low cross-talk 2 × 2 silicon electro-optic switch matrix based on a double-gate configuration is proposed and experimentally demonstrated. The switch matrix consists of four Mach-Zehnder-based 2 × 2 switching elements with 400 μm long modulation arms. Low cross-talk values of -31 and -43 dB are, respectively, obtained for the "cross" and "bar" states over a 40 nm wide wavelength range around 1550 nm. The values for the total steady-state power consumption of the "cross" and "bar" states are 40.8 and 19.1 mW, respectively.

Regenerative polymeric bus architecture for board-level optical interconnects

A scalable multi-channel optical regenerative bus architecture based on the use of polymer waveguides is presented for the first time. The architecture offers high-speed interconnection between electrical cards allowing regenerative bus extension with multiple segments and therefore connection of an arbitrary number of cards onto the bus. In a proof-of-principle demonstration, a 4-channel 3-card polymeric bus module is designed and fabricated on standard FR4 substrates. Low insertion losses (≤ -15 dB) and low crosstalk values (< -30 dB) are achieved for the fabricated samples while better than ± 6 µm -1 dB alignment tolerances are obtained. 10 Gb/s data communication with a bit-error-rate (BER) lower than 10(-12) is demonstrated for the first time between card interfaces on two different bus modules using a prototype 3R regenerator.

Design of 4x4 Banyan optical switch using optoelectronic MZI switches with low crosstalk.

We introduce here a designing of 2x2 MZI (Mach-Zehnder Interferometer) optical switch. The switching of the optical signal is realized with the use of fast electro-optical effects. The designed model has a very high switching capability and is extremely reliable. Various design parameters have been varied to improve the performance of the switch. Then the basic 2×2 switch is exploited in design of 4×4 banyan switch. Banyan switch is a good candidate for further use in higher order switches. Simulation results are shown for 2×2 and 4×4 banyan architecture with low cross-talk values.

Fiber Bragg grating–based self-referencing technique for wavelength-multiplexed intensity sensors

An amplitude-phase-conversion self-referencing technique for intensity-modulated photonic sensors that uses two different-wavelength fiber Bragg gratings is presented. With this technique, the system response has been demonstrated to be almost unafffected by network power variations as high as 90% of the total power launched by the source. We prove the multiplexing capability of this type of self-referenced fiber sensor by wavelength-division multiplexing two of them in a star network. A tunable fused biconical wavelength-division multiplexer is used for sensor addressing at the detection block, providing both good isolation and low cross-talk values.

Waveguide crossings with low crosstalk at small angles

Waveguide crossings with different small crossing angles were simulated and experimentally investigated on a silica-on-silicon platform. To achieve low crosstalk a region at small angles besides the generally used regime can be found. The affiliated angles are about a factor of 3 smaller than the angles conventionally applied to achieve comparable low crosstalk values. This offers a way to realise more compact devices.

Very low crosstalk 1×2 digital optical switch integrated with variable optical attenuators

A novel digital thermo-optic switch based on a polymer waveguide has been demonstrated. The proposed switch consists of a conventional 1/spl times/2 digital optical switch and compact variable optical attenuators, with both elements integrated in series. The switches exhibit very low crosstalk values of -42 and -40 dB, and the switching power is /spl sim/170 mW at 1.5 /spl mu/m.

Low-crosstalk arrayed-waveguide grating multi/demultiplexer with phase compensating plate

The crosstalk of an arrayed-waveguide grating multi/demultiplexer was reduced by employing a phase compensating plate developed for static phase control. Experimental results showed low crosstalk values of –37 and –39 dB for the TE and TM modes, respectively, in an 8 × 8 100 GHz-spacing arrayed-waveguide grating multi/demultiplexer. This novel method offers polarisation independent phase control for a closely arranged waveguide array.

Optical receiver systems for high speed parallel digital data links

This paper presents an analysis as well as experimental results on developing receiver arrays for parallel digital datalinks for 10-100 m in the Gb/s range. Interchannel crosstalk can be a dominant limiting factor on the bit-error-rate in such parallel arrays. We present a novel analysis of the physical origins of crosstalk arising from the power-supply distribution, as well as an efficient circuit simulation technique for the effect of crosstalk on digital signal transmission in multichannel systems. It is shown that while differential receivers exhibit a far lower crosstalk than single-ended ones, it is possible to obtain low crosstalk values in the latter case by means of suitable power supply decoupling. Experimental results in the form of two low crosstalk multichannel receiver arrays are presented to corroborate the theory. >

Recording Properties of Magneto-Optical Disks with Metal Guiding Layers

The track pitch of magnetooptical disks with metal guiding layers was reduced to less than the laser spot size by suppressing crosstalk. The recorded domain width was effectively confined by the width of the spiral-shape recording region from which the guiding layer was removed. The CNR was improved by using a substrate/enhancing layer/guiding layer/interference layer/recording layer structure. The total thickness of the enhancing and interference layers was adjusted in order to increase the Kerr effect enhancement, and a CNR of 47.1 dB at 3.73 MHz was obtained for a track pitch of 1.0 μm. Low crosstalk values of less than -28.8 dB and -26.2 dB were achieved at 1.0 MHz for track pitches of 1.0 and 0.9 μm respectively, using a conventional optical head having an objective lens of 0.53 NA and a 780 nm laser.

金属案内層付き光磁気ディスクの記録特性

The track pitch of magneto-optical disks with metal guiding layers was reduced to less than the laser spot size by suppressing crosstalk. The recorded domain width was effectively confined by the width of the recording region in which the guiding layer was spirally removed. Improvement of the CNR was achieved by using the structure of substrate/enhancing layer/guiding layer/interference layer/recording layer. The total thickness of the enhancing and interference layers was adjusted in order to increase the Kerr effect enhancement, and a CNR of 47.1dB at 3.73 MHz was obtained for a track pitch of 1.0μm. Low crosstalk values of less than -28.8 dB and -26.2 dB were achieved at 1.0 MHz for track pitches of 1.0 and 0.9μm, respectively, with a conventional optical head having an objective lens of 0.53 NA and a 780-nm laser.