High-performance guided-wave multi/demultiplexer based on novel design using embedded gradient-index waveguides in glass

A guided-wave multi/demultiplexer which comprises low-loss gradient-index ion-exchange waveguides embedded in a glass substrate and optimised interference filters was successfully fabricated. Around ? 1dB insertion losses for demultiplexing and less than 2dB insertion losses for multiplexing with sufficient transmission bandwidth as wide as 66 nm were achieved.     

Active lossless monolithic one-by-four splitters/combiners usingoptical gates on InP

Active one-by-four splitters/combiners were fabricated on InP from the monolithic integration of waveguides and amplifiers. The device exhibited propagation loss below 1.5 dB·cm^-1, S-bend loss of 0.2 dB per bend, a 3-dB optical bandwidth of 23 nm, a mean optical crosstalk and extinction ratio of, respectively, 37 dB and 42 dB. On all paths, at least 0 dB insertion loss (fiber to-fiber gain up to 2.8 dB) as well as a low polarization sensitivity (below 1.0 dB) were demonstrated. This device can be used as the basic building block of bit-rate transparent switches for optical routing and broadcasting     

Stacked polymeric multimode waveguide arrays for two-dimensional optical interconnects

Two-dimensional (2-D) polymeric multimode waveguide arrays with two reflection-mirrors have been fabricated for optical interconnects between 2-D arrayed vertical-cavity surface-emitting lasers and detectors. Contact printing lithography was adopted for simple and low-cost process using ultraviolet-curable epoxy-based polymers. Fabricated waveguides were diced of the same size and stacked one by one with lateral positional errors less than /spl plusmn/20 /spl mu/m. Two kinds of mirrors were fabricated: single-reflection mirror and double-reflection mirror. Double-reflected mirrors resulted in lower losses with 1.2 dB than single reflected mirrors with 2.1 dB. The average insertion losses of 16-channel arrayed waveguides with two single-reflection mirrors and with two double-reflection-mirrors were measured to be 6.1 and 4.4 dB for 6-cm-long waveguides at a wavelength of 830 nm, respectively. The crosstalk between the waveguides was less than -25 dB. The characteristics of the waveguide arrays are good enough for applications to optical interconnects.     

Fabrication of 64×64 arrayed-waveguide grating multiplexer onsilicon

A 64 channel arrayed-waveguide multiplexer with 0.4 nm (50 GHz) channel spacing at 1.55 μm has been fabricated using SiO₂-Si waveguides. The authors obtained a crosstalk of less than -27 dB to neighbouring and all other channels. The on-chip insertion loss ranges from 3.1 to 5.7 dB for central and peripheral output ports, respectively     

Low-loss near-infrared passive optical waveguide components formedby electron beam irradiation of silica-on-silicon

Results are presented for a range of near infrared single-mode passive channel waveguide optical components fabricated in PECVD silica-on-silicon by electron beam irradiation. The devices include S-bends, Mach-Zehnder interferometers, Y-junction tree-structured splitters, and directional couplers. It is shown that low loss may be obtained through appropriate choice of waveguide bend radius and fabrication parameters; fiber-device insertion losses of ≈2 dB and ≈1 dB are achieved for 1×8 splitters and 3-dB directional couplers, respectively, at λ=1.525 μm     

Integrated polarization diversity front end optics

The integration of a polarization-diversity receiver front-end suitable for balanced detection has been realized by the hybrid combination of a 3-dB directional coupler and a thin-film polarization beam splitter (PBS) fabricated on silica-based waveguides. Insertion losses, excluding the intrinsic loss of the coupler, were 1 and 1.2 dB for TE- and TM-polarizations, respectively. The polarization cross talk was less than -23 dB     

Characteristics of S-shaped waveguide structures by the annealedproton exchange process in LiNbO3

The loss of S-shaped waveguide bends in annealed proton-exchanged LiNbO₃ integrated optical devices is found to be dependent on the length of thermal annealing time. The minimum transition length required in order to have losses as low as 0.2 dB is 2.0 mm for a 0.1-mm lateral offset. Intersecting waveguides based on S-shaped structures have been characterized for passive crossovers. An angle greater than 6° is required to provide a crosstalk of less than -30 dB. At a particular angle, intersecting waveguides offer the possibility of making a 3-dB coupler if an insertion loss of 1.2 dB is not a big concern. Zero-gap couplers based on S-shaped structures have been characterized for applications as 3-dB couplers as well. This type of 3-dB coupler has a much lower insertion loss of roughly 0.4-0.5 dB. Both 3-dB intersecting waveguides and 3-dB zero-gap couplers are less sensitive to wavelength variations     

A 45-channel 100 GHz AWG based on Si nanowire waveguides

A 45-channel 100 GHz arrayed waveguide grating (AWG) based on Si nanowire waveguides is designed, simulated and fabricated. Transfer function method is used in the spectrum simulation. The simulated results show that the central wavelength and channel spacing are 1 562.1 nm and 0.8 nm, respectively, which are in accord with the designed values, and the crosstalk is about ?23 dB. The device is fabricated on silicon-on-insulator (SOI) substrate by deep ultraviolet lithography (DUV) and inductively coupled plasma (ICP) etching technologies. The 45-channel 100 GHz AWG exhibits insertion loss of 6.5 dB and crosstalk of ?8 dB. This work has been supported by the National High Technology Research and Development Program of China (No.2015AA016902), and the National Natural Science Foundation of China (Nos.61435013 and 61405188). E-mail:zhangjiashun@semi.ac.cn      

Adiabatic 3-dB couplers, filters, and multiplexers made with silicawaveguides on silicon

The performance of adiabatic 3-dB couplers and V-branches is reported. These devices are broadband and divide power equally. They have no observable polarization dependence. Typical excess losses relative to a straight waveguide is 0.1-0.2 dB for the 3-dB couplers and about 0.4 dB for the V-branches. Fiber to fiber insertion loss of 0.31 dB was measured for a 2.5-cm straight waveguide. The devices were used to fabricate transmission filters peaked at 1.55 μm and power combiners having two channels at 1.48 and 1.55 μm. The device fabrication was improved by use of a flowable top cladding layer containing boron and phosphorous which easily filled-in between closely spaced waveguides     

Design of Nonradiative Dielectric Waveguide Filters (Short Papers)

An efficient design technique of nonradiative dielectric waveguide filters for use at millimeter wavelengths is developed. Filter stuctures considered here are a gap-coupled type and an altenating-width type. According to present theory, 3-pole, 0.1-dB Chebyshev ripple bandpass filters with a 2-percent bandwidth at a center frequency of 49.5 GHz were designed and fabricated with Teflon dielectric. Calculated and measured filter responses agree quite well, and excess insertion losses are found to be as small as 0.3 dB for both types of the fabricated filter circuits.     

基于硅纳米线波导的16通道200GHz阵列波导光栅

设计了基于硅纳米线波导的16通道,通道间隔为200GHz的阵列波导光栅(AWG)。传输函数法模拟了器件传输谱,结果表明器件的通道间隔为1.6nm,通道间串扰为31dB。器件利用SOI材料,由193nm深紫外光刻工艺制备。光谱测试结果分析表明,通道串扰为5-8dB,中心通道损耗2.2dB,自由光谱区长度24.7nm,平均信道间隔1.475nm。详细分析了器件谱线畸变的原因。     

16 channel 200 GHz arrayed waveguide grating based on Si nanowire waveguides

A 16 channel arrayed waveguide grating demultiplexer with 200 GHz channel spacing based on Si nanowire waveguides is designed.The transmission spectra response simulated by transmission function method shows that the device has channel spacing of 1.6 nm and crosstalk of 31 dB.The device is fabricated by 193 nm deep UV lithography in silicon-on-substrate.The demultiplexing characteristics are observed with crosstalk of 5-8 dB,central channel’s insertion loss of 2.2 dB,free spectral range of 24.7 nm and average channel spacing of 1.475 nm.The cause of the spectral distortion is analyzed specifically.     

Fabrication of buried channel waveguides in fused silica usingfocused MeV proton beam irradiation

Low-loss channel waveguides have been fabricated in fused silica using a beam of MeV protons focused down to a spot size of several microns. By using a combination of beam and sample scanning, single- and multimode graded index waveguides with lateral dimensions down to approximately 5 μm×5 μm have been fabricated using ion doses in the range (3×10¹⁴)-(6×10¹⁶) ions/cm ². Typical beam currents in the range 100 pA-10 nA were used. Optical mode profiles have been measured at 670 nm and propagation losses of the order of 3 dB/cm measured in unannealed samples. Annealing the substrate for 1 h at 500°C reduced these losses to below 0.5 dB/cm     

0.1 dB/cm waveguide losses in single-mode SOI rib waveguides

Waveguide losses as low as 0.1 dB/cm at a wavelength of /spl lambda/=1.3 /spl mu/m have been achieved in SOI rib waveguides fabricated by wet chemical etching. The single-mode waveguides have a large cross section yielding field mismatch losses to a standard single-mode fiber of only 0.17 dB/facet (both polarizations). Polarization independent fiber-chip-fiber insertion losses of 0.9 dB (best 0.5 dB) at a chip length of 60 mm have been measured.     

Wide passband grating multiplexer for multimode fibers

A grating multiplexer in Littrow-configuration is presented, whose passband width-normalized to channel spacing-is comparable with grating demultiplexers. As shown by calculation, a wide passband is attainable by very small input fiber spacing. Using a standard-(50/125 mum)-GI-fiber as transmission fiber, a 1-dB pass-band of 30 nm with a channel spacing of 46 nm is achieved in an 8- channel device. The insertion losses for each channel are in the range 1.4-2.5 dB for 8- or 10-channel devices.     

Reconfigurable 16-channel WDM drop module using silicon MEMSoptical switches

A reconfigurable 16-channel 100-GHz spacing wavelength-division-multiplexed drop module for use at 1550 nm was demonstrated using silicon microelectromechanical system (MEMS) optical switches and arrayed waveguide grating routers. Through-channel extinction was greater than 40 dB and average insertion loss was 21 dB, Both drop-and-retransmit of multiple channels (11-18 dB contrast, 14-19-dB insertion loss) and drop-and-detect of single channels (>20-dB adjacent channel rejection, 10-14-dB insertion loss) were implemented     

Low-loss wavelength division multiplexing (WDM) devices for single-mode systems

We report here on single-mode microoptic wavelength division multiplexing (WDM) devices with two channels located at 1275 and 1345 nm, respectively. Data are presented for four multiplexers and four demultiplexers. The average insertion loss for the multiplexers was 0.5 ± 0.2 and 1.0 ± 0.3 dB for the short and long wavelength channels, respectively. For the demultiplexers, the average losses were 0.8 ± 0.2 dB and 1.0 ± 0.1 dB, respectively. The full channel widths of the demultiplexers for 0.5 dB of additional loss were about 22 nm. All measurements included the presence of prototype precision single-mode connectors. The multiplexers were based on interference filters and GRIN lenses with identical single-mode fibers used for inputs and output. The demultiplexers employed diffraction gratings and GRIN lenses with 50- μm core graded-index output fibers. In addition three of the demultiplexers included a third output channel centered at 1521 nm. The 28- dB dynamic range of the monochromator-based test appartus was insufficient to evaluate the crosstalk performance. Measurements on two demultiplexers, using a 1295-nm laser, yielded values of -33 and -38 dB, respectively for the crosstalk in the 1345-nm channel.     

Fabrication of nickel stamp with improved sidewall roughness for optical devices

We proposed the simple and attractive fabrication method of nickel stamp with improved sidewall roughness for polymeric optical devices. For this, the imprinted optical devices patterns under optimum imprinting conditions were annealed to improve the sidewall roughness generated by the DRIE process in the silicon stamp fabrication. The annealed sidewall roughness is reduced to 24.6 nm, nearly decreasing by 76% compared with the result before the annealing. Then, low cost and durable nickel stamp with improved sidewall roughness was fabricated by the annealed polymeric patterns being used as original master for electroforming process. And, we verified the superiority of the improved nickel stamp by comparing the optical propagation losses for optical waveguides to be fabricated, respectively, using the nickel stamp and original silicon stamp. The optical waveguides fabricated by the imprint lithography using the improved nickel stamp was demonstrated that their optical losses were reduced as 0.21 dB/cm, which was less than the propagation loss for polymeric waveguides using the conventional original silicon stamp. This result could show the effectiveness of the fabricated nickel stamp with improved sidewall roughness. Furthermore, we were able to successfully fabricate a polymeric 1 × 8 beam splitter device using the improved nickel stamp. And, the insertion loss for eight channels obtained to be from 10.02 dB to 10.91 dB.     

A manufacturable technique for implementing low-loss self-imagingwaveguide beamsplitters

A manufacturable technique to implement self-imaging waveguide beamsplitters is proposed and demonstrated. This technique offers low insertion loss and polarization crosstalk, uniform splitting ratios, ease in manufacture, and most importantly application to diverse waveguide material systems. Beamsplitters with splitting ratios that range from 1×2 through 1×17 were fabricated in GaAs-AlGaAs waveguides. For 1×16 splitters integrated with an output ridge waveguide array, the insertion losses in many devices were less than the insertion losses in adjacent straight-through ridge waveguides. The best uniformity spread among the 16 channels was 17.8% and the TE-to-TM and TM-to-TE polarization crosstalks were lower than -25 dB     

Thermo-optically tunable arrayed-waveguide-grating made of polymer/Si

Inthe future,optical communication systems will usemore exceptional optical fiber with high bandwidth.Dense wavelength division multiplexing(DWDM)isconsidered as a promising solution to the demand fortransportingterabits ofinformation viafibers[1].Arrayed…