Extremely low-loss 1.5%-/spl Delta/ 32-channel athermal arrayed-waveguide grating multi/demultiplexer

A silica-based 1.5%-/spl Delta/ 100 GHz-spacing 32-channel athermal arrayed-waveguide grating (AWG) with compact size and extremely low insertion loss is described. By reducing the fibre coupling loss and the excess loss in a silicone-filled groove, an insertion loss of 1.3 dB was achieved with this athermal AWG.     

Athermal Mach-Zehnder interferometer-synchronised arrayed waveguide grating multi/demultiplexer with low loss and wide passband

Described is a silica-based athermal 100 GHz-spacing 40-channel arrayed waveguide grating (AWG) with a Mach-Zehnder interferometer (MZI)-synchronised configuration that employs resin-filled grooves in the AWG and MZI. By suppressing the groove excess loss and using 1.5%-Delta waveguides, a low insertion loss of 3.2 dB and a wide 0.5 dB bandwidth of 45.9 GHz with athermal operation in the -5 to 65degC range and a compact chip size were achieved.     

Super-high-/spl Delta/ athermal arrayed waveguide grating with resin-filled trenches in slab region

A small and low-loss athermal AWG is demonstrated based on super-high-/spl Delta/ waveguides. Resin-filled trenches are formed in the slab region to compensate for the temperature-dependent wavelength shift. Small wavelength shift of 0.03 nm is achieved for the temperature range 0-65/spl deg/C with almost no spectral degradation.     

Athermal silica-based arrayed-waveguide grating (AWG)multi/demultiplexers with new low loss groove design

A new low loss groove design for athermal silica-based AWG multi/demultiplexers is proposed. The insertion loss was <3.2 dB with an excess loss of 0.4 dB. The temperature dependence of the channel wavelength change was suppressed to be below 2.5 GHz in the 0-85°C range     

Spot-size converter using vertical ridge taper for low fibre-coupling loss in 2.5%-/spl Delta/ silica waveguides

A novel spot-size converter based on a vertical ridge waveguide taper for super-high-/spl Delta/ silica waveguides is demonstrated. This structure can be formed with a simple fabrication process. The coupling loss between a singlemode fibre and a 2.5%-/spl Delta/ silica waveguide was reduced to 0.31 dB/point compared to 2.7 dB/point for conventional straight waveguides.     

Reducing the thermal dependence of silica-based arrayed-waveguide grating using inorganic-organic hybrid materials

This study demonstrates the application of a temperature-independent arrayed-waveguide grating (AWG) using a simple hybrid waveguide structure composed of silica core/inorganic-organic hybrid material overcladding layer. The thermooptic effect of the hybrid materials varies over a wide range of temperature and provides athermal characteristics in an AWG. The temperature dependence of the AWG was reduced through the precision control of the thermooptic coefficient of the hybrid materials (/spl Delta//spl lambda/=/spl sim/3pm//spl deg/C).     

Compact and low-loss arrayed waveguide grating module with tolerance-relaxed spot-size converter

A compact, low-loss arrayed waveguide grating (AWG) module was achieved by adopting a novel optical spot-size converter (SSC) to planar lightwave circuits (PLCs). The SSC is a laterally tapered waveguide that can be fabricated simply by the conventional fabrication process. The structure is composed of a core width converting region where the spot-size is converted efficiently, and a core width fine-tuning region where the cut-position tolerance is relaxed. We have applied this structure to a 1.5%-/spl Delta/ silica-based waveguides and reduced the single-mode fiber coupling loss to less than 0.5 dB/point. The SSC provides a large cut-position tolerance that enables angle polishing of the PLC endfaces to prevent reflection and low-loss connection of pigtail fibers. The center channel insertion loss of the AWG module was reduced from 4.2 to 2.2 dB, and the reflection was less than -60 dB.     

1.5-/spl mu/m InGaAsP-InP slab-coupled optical waveguide lasers

We report the demonstration of high-power semiconductor slab-coupled optical waveguide lasers (SCOWLs) operating at a wavelength of 1.5 /spl mu/m. The lasers operate with large (4/spl times/8 /spl mu/m diameter) fundamental mode and produce output power in excess of 800 mW. These structures have very low loss (/spl sim/0.5 cm/sup -1/) enabling centimeter-long devices for efficient heat removal. The large fundamental mode allows 55% butt-coupling efficiency to standard optical fiber (SMF-28). Comparisons are made between SCOWL structures having nominal 4- and 5-/spl mu/m-thick waveguides.     

Design and fabrication of ultra-small overlapped AWG demultiplexer based on /spl alpha/-Si nanowire waveguides

A novel layout for an ultra-compact arrayed-waveguide grating (AWG) demultiplexer is presented. The present layout has two overlapped free propagation regions, and is more compact than a conventional layout. Using /spl alpha/Si-on-SiO/sub 2/ nanowire waveguides, an ultra-small 4/spl times/4 AWG (about 40/spl times/50 /spl mu/m/sup 2/) with channel spacing of 11 nm is fabricated and characterised.     

Low-loss athermal silica-based lattice-form interleave filter with silicone-filled grooves

We describe a low-loss athermal silica-based interleave filter with a lattice-form structure. We athermalize the filter by using a silicone-filled groove formed in each delay line and we employ a low-loss design to reduce the accumulated groove excess loss in the multiple delay lines. By using these designs, we obtained a very low groove excess loss of 0.4 dB and achieved satisfactory temperature insensitivity and optical characteristics with this filter.     

Super compact optical add-drop multiplexer for FTTH applications based on low-loss polymer waveguide materials

Four- and eight-channel arrayed-waveguide grating (AWG) and fixed optical add-drop multiplexer (OADM) devices with channel spacing of 1200 and 600 GHz have been fabricated using super-high refractive index contrast (/spl Delta/n=0.020) triazine containing polymers. Accordingly, the size of the four-channel AWG was only 10/spl times/3 mm and the insertion loss was 3 dB.     

Athermal all-polymer arrayed-waveguide grating multiplexer

An athermal arrayed-waveguide grating (AWG) multiplexer relying on an all-polymer approach is reported. The all-polymer AWG consisting of polymer waveguides fabricated on a polymer substrate exhibits excellent performance. By properly adjusting the coefficient of thermal expansion of the polymer substrate, athermal and polarisation-independent AWG devices featuring a wavelength shift of less than ±0.05 nm in the 25-65°C temperature range could be demonstrated     

Lattice-form CWDM interleave filter using silica-based planar lightwave circuit

We demonstrate an eight-channel coarse wavelength-division-multiplexing interleave filter that employs a silica-based lattice-form filter. The filter incorporates phase-generating couplers to convert a conventional frequency interleave filter into a wavelength interleave filter with a constant channel spacing with respect to wavelength. We fabricated the designed interleave filter on a 1.5%-/spl Delta/ silica-based waveguide and realized a constant channel spacing of 20 nm with a wavelength displacement of within /spl plusmn/0.5 nm and an insertion loss of less than 1.7 dB over eight channels.     

Compensation for Second-Order Temperature Dependence in Athermal Arrayed-Waveguide Grating Realizing Wide Temperature Range Operation

We propose a new compensation technique for the second-order temperature dependence in a silica-based arrayed-waveguide grating (AWG) multi/demultiplexer with a resin-filled groove that realizes a wide operating temperature range. We newly employ an additional interferometer in the input port and control the optical field perturbation by using a first-mode lightwave at the entrance to the first slab waveguide. We employ the design to fabricate a 32-channel 100-GHz-spacing athermal AWG that is as compact as a conventional AWG, and demonstrate a reduction in the passband wavelength variation from 70 to 22 pm over an extended $-$ 40 $^{circ}hbox{C}$ to 80 $^{circ}hbox{C}$ temperature range.      

基于SOI的2×2 MMI耦合器的设计

设计了一种可用于阵列波导光栅(AWG)解调集成微系统的绝缘体上硅(SOI)基2×2多模干涉(MMI)耦合器,用光束传播法(BPM)对MMI耦合器进行了模拟。耦合器输入/输出波导采用倒锥形,多模干涉区尺寸为6μm×57μm。在TE偏振中心波长为1.55μm时,器件附加损耗为0.46dB,不均匀性为0.06dB。在1.49～1.59μm波长范围内耦合器的附加损耗小于1.55dB。仿真结果表明所设计的2×2MMI耦合器体积小、附加损耗低、波长响应范围宽、分光均匀,符合片上集成系统的要求。     

1-GHz-spaced 16-channel arrayed-waveguide grating for a wavelength reference standard in DWDM network systems

We fabricated a 1-GHz-spaced 16-channel arrayed-waveguide grating (AWG) by using a new AWG configuration where the path of each arrayed waveguide winds backward and forward across a 4-in diameter wafer without crossing any other waveguides. The ultra-narrow (< 1 GHz) and stable transmission bands of this AWG can be used to construct a wavelength reference standard covering the S, C, and L bands in the dense wavelength-division-multiplexing network systems whose frequency deviation is /spl plusmn/160 MHz.     

The AWG/spl par/PSC network:a performance-enhanced single-hop WDM network with heterogeneous protection

Single-hop wavelength-division-multiplexing (WDM) networks based on a central passive star coupler (PSC) or arrayed-waveguide grating (AWG) hub have received a great deal of attention as promising solutions for the quickly increasing traffic in metropolitan and local area networks. These single-hop networks suffer from a single point of failure: if the central hub fails, then all network connectivity is lost. To address this single point of failure in an efficient manner, we propose a novel single-hop WDM network, the AWG/spl par/PSC network. The AWG/spl par/PSC network consists of an AWG in parallel with a PSC. The AWG and PSC provide heterogeneous protection for each other; the AWG/spl par/PSC network remains functional when either the AWG or the PSC fails. If both AWG and PSC are functional, the AWG/spl par/PSC network uniquely combines the respective strengths of the two devices. By means of analysis and verifying simulations we find that the throughput of the AWG/spl par/PSC network is significantly larger than the total throughput obtained by combining the throughput of a stand-alone AWG network with the throughput of a stand-alone PSC network. We also find that the AWG/spl par/PSC network gives over a wide operating range a better throughput-delay performance than a network consisting of either two load sharing PSCs in parallel or two load sharing AWGs in parallel.     

Continuous-time /spl Delta//spl Sigma/ modulators using distributed resonators

We derive a method for using distributed resonators in /spl Delta//spl Sigma/ modulators and demonstrate these /spl Delta//spl Sigma/ modulators have several advantages over existing /spl Delta//spl Sigma/ modulator architectures. Like continuous-time (CT) /spl Delta//spl Sigma/ modulators, the proposed /spl Delta//spl Sigma/ modulators do not require a high-precision track-and-hold, and additionally can take advantage of the high-Q of distributed resonators. Like discrete-time /spl Delta//spl Sigma/ modulators, the proposed /spl Delta//spl Sigma/ modulators are relatively insensitive to feedback loop delays and can subsample. We present simulations of several types of these /spl Delta//spl Sigma/ modulators and examine the challenges in their design.     

A 1.5-V 12-bit power-efficient continuous-time third-order /spl Sigma//spl Delta/ modulator

This paper presents the design strategy, implementation, and experimental results of a power-efficient third-order low-pass /spl Sigma//spl Delta/ analog-to-digital converter (ADC) using a continuous-time (CT) loop filter. The loop filter has been implemented by using active RC integrators. Several power optimizations, design requirements, and performance limitations relating to circuit nonidealities in the CT modulator are presented. The influence of the low supply voltage on the various building blocks such as the amplifier as well as on the overall /spl Sigma//spl Delta/ modulator is discussed. The ADC was implemented in a 3.3-V 0.5-/spl mu/m CMOS technology with standard threshold voltages. Measurements of the low-power 1.5-V CT /spl Sigma//spl Delta/ ADC show a dynamic range and peak signal-to-noise-plus-distortion ratio of 80 and 70 dB, respectively, in a bandwidth of 25 kHz. The measured power consumption is only 135 /spl mu/W from a single 1.5-V power supply.