Polarisation-insensitive arrayed-waveguide grating multiplexer withSiO2-on-SiO2 structure

An arrayed-waveguide grating multiplexer with SiO₂-on-SiO₂ structure is fabricated in order to achieve polarisation insensitivity. A negligible wavelength response dependence on polarisation of 0.01 nm, which corresponds to a birefringence of-9×10^-6, is realised in a 16 channel arrayed-waveguide grating multiplexer with a wavelength spacing of 0.8 nm     

A novel ultracompact two-mode-interference wavelength division multiplexer for 1.5-/spl mu/m operation

A novel ultracompact 2/spl times/2 wavelength division multiplexer (WDM) for 1.55-/spl mu/m operation based on highly dispersive two-mode interference (TMI) was designed, theoretically modeled, and verified using a finite-difference-time-domain (FDTD) method. A two-moded waveguide assisted with a dispersive tooth-shaped grating provided a mode-dependent reflection band of central wavelength at 1.55 /spl mu/m. The wavelengths of 1538 and 1572 nm that were at the band edges and had the lowest reflection losses and relatively high dispersion were selected for wavelength multiplexing. The result showed that the wavelengths were separated by grating dispersion in a coupler length of 75 /spl mu/m which was much shorter than the required length of 1.1 mm in a regular TMI multiplexer of no grating. Insertion loss of about 1.7 dB and channel contrast of about 12 dB were achieved.     

Reflective arrayed waveguide grating multiplexer

A high-performance reflective arrayed waveguide grating multiplexer/demultiplexer designed for compatibility with silicon integrated circuit processing is described. The grating, folded by a flat reflecting surface, can be printed in a single-exposure field of a photolithographic stepper. Advanced plasma assisted deposition is used to prepare waveguides with very low loss and minimum birefringence. Multiplexers with 40 channels separated by 100 GHz show intrinsic insertion losses of -2.4 dB, channel uniformity less than 0.6 dB, and very low polarization dependent wavelength shift of 0.012 nm.     

17×17信道光谱响应平坦化的聚合物阵列波导光栅的研制

选用氟化聚芳醚FPE聚合物材料,设计并制备出了17×17信道光谱响应平坦化阵列波导光栅（AWG）波分复用器. 实验测试结果表明,器件的中心波长为1550.83nm,波长间隔为0.8nm, 3dB带宽约为0.476nm,插入损耗为13~15dB,串扰低于-21dB.     

A wavelength division multiplexer based on plastic surfacerelief grating applied to local area communication network

A plastic surface-relief grating as a wavelength division multiplexer is designed and fabricated with the conventional mould pressing technique using the transmission-type fused quartz phase grating as mask pattern and polycarbonate as basal material.The experiment results show that in an optimizing process,the plastic surface-relief grating has the highest firstorder diffraction efficiency under adequate groove depth and incident angle,and can be used as the best optical path for wavelength division multiplexing(WDM).We also establish the experiment setup for testing the WDM performance of the plastic surface-relief grating based wavelength division multiplexer.The results show that the proposed wavelength division multiplexer has the high-stability temperature characteristics,the low insertion loss of less than 5 dB,the large isolation of greater than 20 dB,the low polarization-dependent loss(PDL) of less than 0.4 dB and the relatively steep pass-band characteristics.It is a WDM device with good performance,which can be applied in short distance communication.     

Optical grating multiplexer in the 1.1?1.5 ?m wavelength region

Experimental results of a multiplexer using a diffraction grating for a wavelength-division-multiplexing transmission system are described. The multiplexer has 10 channels and a wavelength spacing of 36.2 nm in the 1.1?1.5 ?m wavelength region. Minimum insertion loss for each channel was less than 2.2 dB.     

Demonstration of a 15×15 arrayed waveguide multiplexer on InP

By interconnecting two star couplers with a waveguide grating, the authors built a monolithic 15×15 multiplexer on InP. The grating order of 148 gives a free spectral range of 10.5 nm (1.3 THz) and a channel spacing of 0.7 nm (87 GHz) at 1550 nm wavelength. A crosstalk between adjacent channels of less than 18 dB and a residual crosstalk of less than 25 dB were obtained. The on-chip insertion loss is typically 2-4 dB     

Arrayed-waveguide grating multiplexer with loop-back optical pathsand its applications

We present a basic configuration of an unique integrated-optic arrayed-waveguide grating (AWG) multiplexer with loop-back optical paths and demonstrate an add-drop multiplexer (ADM), a network access terminal, and a wavelength channel selector for dense-WDM ring or bus networks, as three useful examples of its attractive applications. A key device in these components is a silica-glass based 1.55 μm polarization-insensitive 32×32 AWG multiplexer chip with 0.8 nm channel spacing which is fabricated using planar lightwave circuit (PLC) technologies. Fine operation in their new functional components is achieved by using the AWG multiplexer module having low insertion loss of 3.9 dB and low interchannel crosstalk of less than -28 dB     

Arrayed waveguide grating of 70/spl times/60 /spl mu/m/sup 2/ size based on Si photonic wire waveguides

A miniature arrayed waveguide grating of 70/spl times/60 /spl mu/m/sup 2/ size consisting of Si photonic wire waveguides was designed using complete modelling in the finite-difference time-domain simulation. The device was fabricated onto a silicon-on-insulator substrate and evaluated in the wavelength range around 1.55 /spl mu/m. The clear demultiplexing characteristics were observed with a channel spacing of 11 nm and a loss of less than 1 dB.     

Low Rayleigh scatteringP2O5-F-SiO2 glasses

The Rayleigh scattering and infrared absorption losses of P₂ O₅-F-doped silica glass, which is a candidate material for ultra-low-loss optical fiber, were investigated experimentally. The Rayleigh scattering loss of 8.5 wt.% P₂O₅ and 0.3 wt.% F-doped SiO₂ glass is found to be 0.8 times that of pure silica glass. It is also found that the infrared absorption property of P₂O₅-F-SiO₂ glass is almost the same as that of pure silica glass. The minimum loss for the proposed composition is estimated to be 0.11 dB/km at 1.55 μm wavelength, and 0.21 dB/km at 1.3 μm wavelength     

A Low-Loss Diffraction Grating Frequency Multiplexer

A quasi-optical frequency multiplexer based on a blazed diffraction grating is studied. Experimental data, supported by semi-quantitative theoretical considerations, show that the multiplexer is an efficient channel-dropping filter well suited to use in the millimeter wave region. A feature of the grating multiplexer which sets it apart from conventional designs is its ability to drop several channels using a single frequency-selective element, namely, a diffraction grating. This economy of hardware results in a simple, compact structure. The channels of the experimental multiplexer have typical bandwidths of ~540 MHz with loss of ~1 dB. The width of the impulse response at half amplitude is ~1.5 ns. Return loss within a channel is typically 15-20 dB. Comparisons with other millimeter wave multiplexer designs are discussed.     

A 12-channel phased-array wavelength multiplexer with multimodeinterference couplers

A compact 12-channel phased-array wavelength-division multiplexer based on multimode interference (MMI) couplers and useful for application with multiwavelength lasers is proposed. A suitably-chosen 1×12 MMI nonuniform power splitter is used to suppress the sidelobes of the multiplexer spectral response. Simulated results for the multiplexer designed in an InP-InGaAsP rib waveguide system and with 1-nm channel spacing at a wavelength of 1550 nm are presented. The multiplexer has a length of 3.2 mm and an insertion loss of 1.7 dB     

Fabrication of (Pb,La)(Zr,Ti)O/sub 3/ thin-film arrayed waveguide grating

The design and fabrication of an 8-ch, 500 GHz-spacing arrayed waveguide grating on (Pb,La)(Zr,Ti)O₃ has been successfully achieved for the first time. An insertion loss of 22.1 dB, including a 10 dB coupling loss, and an adjacent crosstalk of -23.1 dB have been obtained. The device is expected to be monolithically integrated into high-speed optical switches to form integrated chips such as a reconfigurable add-drop multiplexer     

Microoptic grating multiplexers and optical isolators for fiber-optic communications

As new optical devices for increasing further the utility of and to expand the application of fiber-optic communications, grating multiplexers and isolators have been developed for 0.8 μm band employing microoptic approach. The development of these devices is the subject of this paper. The devices have desirable features of small size, compactness, high optical performances, and high reliability. The grating multiplexer consists of a graded-index rod, a blazed reflection grating replicated onto the graded-index rod slanting facet or a wedge facet, and an input-output fiber array. Simple calculations have been done to determine necessary element parameters for a given channel spacing. Experimental results are presented for five-channel multiplexers devised using a SELFOC^®lens. Around 3 dB insertion loss and less than -30 dB crosstalk have been obtained for about 35 nm channel spacing in overall device size of18 times 13 times 50mm. Faraday rotation optical isolators for 0.8 μm band have been miniaturized by employing an efficient paramagnetic glass Faraday rotator, a magnet with a through hole and a folded optics in the Faraday rotator. The path number in the folded optics has been optimized in terms of trading-off between the magnet size and the insertion loss. A 0.9 dB insertion loss including fiber coupling loss and 36 dB isolation have been obtained in overall device size of24 times 24.5 times 42mm. Results on the temperature and wavelength dependence of the isolation are also presented. In addition, fundamental properties of optical circulators for 0.8 μm band and optical isolators and circulators both for 1.3 μm band, developed as extended modifications of the optical isolators for 0.8 μm band, are briefly described.     

Gating demultiplexer integrated with MSM detector array inInGaAs/AlGaAs/GaAs for WDM

The authors demonstrate the integration of a grating demultiplexer with curved output waveguides and a MSM photodetector array in InGaAs/AlGaAs/GaAs operating in the 1-μm wavelength region. The structure provides 38 channels with 1-nm channel spacing. The total loss, including scattering from the unmetallized grating, is about 17 dB. A channel crosstalk of -11 dB is obtained. The FWHM of the channel pass band is 0.5 nm     

Ultra low-loss 1 X 2 multiplexer using thin-film filters on polymer integration platform

Compact 1 X 2 wavelength multiplexer modules employing thin-film filters integrated into polymer planar waveguide circuits are presented. The modules also feature on-chip deep-etched U-grooves for precise fibre-chip coupling. Insertion loss <1 dB, crosstalk <-30 dB, and return loss <-50 dB have been achieved by various technological optimisations.     

Characteristics of Er-doped Al2O3 thin filmsdeposited by reactive co-sputtering

Er-doped Al₂O₃ thin films have been deposited by reactive co-sputtering onto thermally oxidized Si-wafers. The deposition process has been optimized with respect to the requirements originating from the application of these multilayer structures as integrated optical amplifiers for the third telecom window, i.e., the wavelength range 1.52-1.55 μm. The films obtained at a substrate temperature of only 400°C are amorphous and show a homogenous structure, without columns or grains. For slabguides, background losses smaller than 0.25 dB/cm have been obtained, even without any annealing. A relatively broad luminescence band, having an FWHM of ~55 nm around the 1.533-μm wavelength, has been measured. From gain versus pumping power curves, an upconversion coefficient lower then 20·10^-25 m³/s has been derived, being half of the values reported up to now in the literature. Simulations based on experimentally determined material parameters and assuming a channel attenuation of 0.5 dB/cm indicate, for 0.24 at.% Er channel devices with an optimal channel length of 7.7 cm, an amplification of 8 dB at 1.533 μm for a pump wavelength of 1.48 μm, and a pump power of only 8.7 mW     

Enhancement and tuning of fibre Bragg grating reflection by 157 nmF2-laser post exposure

The weak reflectivity (1-2 dB) of a fibre Bragg grating can be significantly amplified (to 14 dB, 96%) in a standard telecommunication fibre by post irradiation with uniform 157 nm F₂-laser radiation. This enhancement, together with wavelength tuning, can be precisely controlled by the post exposure fluence     

Adiabatic 2×2 polarization splitter on LiNbO3

The authors have demonstrated a passive 2×2 polarization splitter in x-cut LiNbO₃, using a hybrid Ti-indiffusion/proton-exchange technology. At a wavelength of 1530 nm, all paths exhibited an extinction ratio of better than 20 dB, with an average excess loss of 1 dB. This component can be integrated with optical filters, switches, and beam combiners to achieve polarization-independent operations     

基于石英衬底的16通道二氧化硅可调复用器/解复用器的单片集成

本文是关于可调复用器/解复用器的单片集成,它由一个16通道200 GHZ的二氧化硅阵列波导光栅和一组马赫增德尔干涉型热光可调光衰减器阵列构成。该集成器件是基于石英衬底的,与基于硅衬底的器件相比,省去了沉积下包层的工艺步骤,并且降低了器件功耗。该集成器件的插入损耗是-5 dB,串扰小于-22 dB。在衰减为20 dB的时候每个通道的功耗只有110 mW。