Athermal Arrayed-waveguide Grating Research Articles

Evaluation of the Reliability and Lifetime Prediction of 150 GHz Athermal AWG Module with Metal Temperature Compensation Board

We have developed a 17-channel (150 GHz-spacing) athermal arrayed waveguide grating (AAWG), which has a wider operation range than that of the existing AWGs, by designing a metal structure assembly that reduces the temperature dependence of the wavelength. For an operation temperature range from −40 °C to 85 °C, the center wavelengths of all channels had a wavelength stability of ±0.04 nm and the insertion loss variation was less than ±0.78 dB. The accelerated life test showed that the predicted service life was expected to be more than 41.7 years.

Integrated athermal arrayed-waveguide grating multiplexer and demultiplexer with all-metal compensating rod for broadband temperature application.

In this paper, a unique device that can act as both multiplexer and demultiplexer is proposed with two all-metal compensating rods that makes the compensated chip almost the same spectrum profile as the original one. In this way a flat-top athermal arrayed-waveguide grating module of 100-GHz×40-ch is successfully fabricated. A small center wavelength shift of ±25 pm is achieved for the ultra-wide temperature range from -40°C to 85°C with the low insertion loss change of less than ±0.14 dB.

Athermal arrayed waveguide gratings in silicon-on-insulator by overlaying a polymer cladding on narrowed arrayed waveguides

Athermal arrayed waveguide gratings (AWGs) in silicon-on-insulator (SOI) are experimentally demonstrated for the first time to our knowledge. By using narrowed arrayed waveguides, and then overlaying a polymer layer, the wavelength temperature dependence of the AWGs is successfully reduced to -1.5 pm/°C, which is more than 1 order of magnitude less than that of normal SOI AWGs. The athermal behavior of the AWGs is obtained with little degradation of their performance. For the central channel, the cross talk is less than -15 dB and the insertion loss is around 2.6 dB. Good characteristics can be maintained with temperatures up to 75 °C. The total size of the device is 350 μm × 250 μm.

Rapid High-Precision In Situ Wavelength Calibration for Tunable Lasers Using an Athermal AWG and a PD Array

This letter presents a simple and rapid high-precision in situ calibration technique for tunable superstructure grating distributed Bragg reflector (SSG-DBR) lasers using a laser driver board with an athermal arrayed waveguide grating (AWG) and a photodetector (PD) array. The experiment demonstrates laser calibration for seven wavelength channels completed in 23 s with a precision of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pm$</tex> </formula> 0.015 nm. This letter describes the details of the system calibration method, the mode competition detection technique, and the calibration time analyses. The presented technique can also apply to other tunable lasers with suitable modification in the laser driver interfaces. <?Pub _bookmark="" Command="[Quick Mark]"?>

Reduction of Second-Order Temperature Dependence of Silica-Based Athermal AWG by Using Two Resin-Filled Grooves

We devise a novel design for an athermal silica-based arrayed-waveguide grating (AWG) to reduce the residual second-order temperature dependence of conventional athermal AWGs with a silicone-filled groove. This athermal AWG has two grooves filled with silicone and polyolefin that compensate for the first- and second-order temperature dependence, respectively. The passband wavelength variation is successfully reduced from 80 to 16 pm in a -40°C ~ +80°C temperature range.

A novel fabrication approach for an athermal array ed-waveguide grating

A novel method for fabricating an athermal AWG is proposed, using a unique apparatus for ITU-T center wavelength adjustment and optical coupling of two cut-parts. UV adhesive or sticky gel is applied into the gap between the cut-elements and the alignment base substrate by capillary infiltration. The spectrum profiles are almost the same as those of the original chip state, and no deterioration is observed resulting from athermalization. Flat-top athermal AWG modules of 100 GHz × 40 ch are fabricated. Over a temperature range of −40 to 85 °C, the center wavelength shift is ±22 pm, and the insertion loss change is less than ±0.11 dB.

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 - 40degC to 80degC temperature range.

Low-Loss and Compact Silica-Based Athermal Arrayed Waveguide Grating Using Resin-Filled Groove

We describe our design and fabrication of a low-loss and compact 1.5%-Delta silica-based athermal arrayed waveguide grating (AWG) using a resin-filled groove. We present the theory of athermal AWG design and clarify the relationship between the AWG design parameters and the groove design required for realizing an athermal condition. We also describe approaches for reducing excess loss in the groove, which are used to optimize the groove and arrayed waveguide designs. We examine the performance of a 40-channel 100 GHz spacing athermal AWG module that employs all of the approaches. We successfully reduce the excess loss in the groove to 0.2 dB and achieve a compact chip size of 31times23 mm2 as well as sufficient optical performance and temperature insensitivity for practical use. In addition, we confirm by calculation that our approaches for excess loss reduction are also effective for an athermal AWG with a channel spacing of less than 100 GHz.

Athermal silicon arrayed waveguide grating with polymer-filled slot structure

In this paper, an athermal silicon arrayed waveguide grating (AWG) with the assistance of a polymer-filled slot structure is proposed. Arrayed slot waveguides were used to replace arrayed silicon photonic wires (SPWs). By carefully controlling the temperature dependence of the effective index of the polymer-filled slot waveguides, the athermal silicon AWG is realized. Analysis shows that the center wavelength shift of the AWG can be down to 0.14 pm/°C.

Arrayed Waveguide Gratings and Their Application Using Super-High-.DELTA. Silica-Based Planar Lightwave Circuit Technology

This paper reviews our recent progress on arrayed wave-guide gratings (AWGs) using super-high-Δ silica-based planar lightwave circuit (PLC) technology and their application to integrated optical devices. Factors affecting the chip size of AWGs and the impact of increasing relative index difference Δ on the chip size are investigated, and the fabrication result of a compact athermal AWG using 2.5%-Δ silica-based waveguides is presented. As an application of super-high-Δ AWGs to integrated devices, a flat-passband multi/demultiplexer consisting of an AWG and cascaded MZIs is presented.

Analytical Solutions to Estimate the Temperature Sensitivity of Arrayed Waveguide Gratings With Stress Plates

Controlling thermal stress is a promising way to reduce the temperature instability of arrayed waveguide gratings (AWGs). A simple method to apply thermal stress is to attach stress plates on the arrayed waveguides. In this paper, a general analytical method to study the temperature sensitivity of the central wavelength in modified AWGs with stress plates is developed. The complete analysis shows that the temperature sensitivity can be controlled effectively by tuning the material parameters and the thickness of the stress plates. To obtain athermal AWGs, a stress plate with large positive thermal expansion coefficient and small Young's modulus should be attached on the bottom of the arrayed waveguides. The material with large negative thermal expansion coefficient suggests another potential scheme.

Demonstration of Compact and Low-Loss Athermal Arrayed-Waveguide Grating Module Based on 2.5%-Δ Silica-Based Waveguides

We demonstrated a compact and low-loss athermal arrayed-waveguide grating (AWG) module utilizing silica-based planar lightwave circuit (PLC) technology. Spot-size converters based on a vertical ridge-waveguide taper were integrated with a 2.5%-Δ athermal AWG to reduce the loss at chip-to-fiber interface. Spot-size converters based on a segmented core were formed around resin-filled trenches for athermalization formed in the slab to reduce the diffraction loss at the trenches. A 16-channel athermal AWG module with 100-GHz channel spacing was fabricated. The use of a 2.5%-Δ athermal chip with a single-side fiber array enabled a compact package of the size of 41.6×16.6×4.5 mm3. Athermal characteristics and a small insertion loss of 3.5–3.8 dB were obtained by virtue of low fiber-to-chip coupling loss and athermalization with low excess loss.

Ultra-small 40-channel athermal arrayed-waveguide grating module with low-loss groove design

An ultra-small athermal arrayed-waveguide grating module with 100 GHz-spacing and 40 channels has been demonstrated by using 2.5%-Delta silica-based waveguides. The module size is only 30 times 10 times 5 mm with a low insertion loss of 2.0-2.9 dB.

Low-loss, flat-passband and athermal arrayed-waveguide grating multi/demultiplexer

We successfully demonstrated a low-loss, flat-passband, and athermal arrayed-waveguide grating (AWG) multi/demultiplexer with a Mach-Zehnder interferometer (MZI) as an input router. Resin-filled trenches were formed in the longer arm of the MZI as well as the slab in the AWG to compensate for the temperature dependence. A 32-channel athermal multi/demultiplexer was fabricated using silica-based planar lightwave circuit (PLC) technology. A small temperature-dependent wavelength shift of 0.02 nm was obtained over the temperature range of -5 to 65 degrees C with low-loss (3.3-3.7 dB) and flat-passband spectra.

Reliable wide-area wavelength division multiplexing passive optical network accommodating gigabit ethernet and 10-Gb ethernet services

This paper proposes and demonstrates a reliable wide-area wavelength-division-multiplexing passive optical network (WDM-PON) with a wavelength-shifted protection scheme. This protection scheme utilizes the cyclic property of 2/spl times/N athermal arrayed-waveguide grating and two kinds of wavelength allocations, each of which is assigned for working and protection, respectively. Compared with conventional protection schemes, this scheme does not need a 3-dB optical coupler, thus leading to ensure the large loss budget that is suited for wide-area WDM-PONs. It also features a passive access node and does not have a protection function in the optical network unit (ONU). The feasibility of the proposed scheme is experimentally confirmed by the carrier-distributed WDM-PON with gigabit Ethernet interface (GbE-IF) and 10-GbE-IF, in which the ONU does not employ a light source, and all wavelengths for upstream signals are centralized and distributed from the central office.

Low‐loss athermal AWG module with high reliability

AbstractWhen building future optical communication networks, athermal and low loss properties continue to be essential demands for arrayed waveguide grating (AWG) which plays the role of a wavelength multiplexer/demultiplexer. To respond to these demands, we developed a low‐loss, 200‐GHz 16‐channel athermal AWG module from low loss techniques and original athermal techniques. The module we developed achieved an insertion loss below 1.4 dB, a center wavelength fluctuation less than ±0.015 nm in all modules in a temperature range from −5°C to 70°C, and an insertion loss fluctuation less than ±0.1 dB. Furthermore, we confirmed that this module has very high reliability from the results of a long‐term reliability test lasting 5000 hours. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 89(3): 26–33, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20213

2.5%-/spl Delta/ silica-based athermal arrayed waveguide grating employing spot-size converters based on segmented core

We describe a novel structure for super-high-/spl Delta/ athermal arrayed waveguide gratings (AWGs) employing spot-size converters based on a segmented core formed in the slab region, to reduce the diffraction loss in resin-filled trenches. This structure requires no depth-tapering process. We demonstrated a compact 16-channel athermal AWG based on the 2.5%-/spl Delta/ silica waveguides. The excess loss due to athermalization was reduced to 0.9 dB with the proposed structure, whereas the excess loss was 2.4 dB using a conventional one. The measured results of the proposed structure show no degradation of the crosstalk and passband shape.

1.5%-/spl Delta/ athermal arrayed-waveguide grating multi/demultiplexer with very low loss groove design

We describe a compact 1.5%-/spl Delta/ athermal silica-based 100-GHz-spacing 16-channel arrayed-waveguide grating (AWG) multi/demultiplexer with a modified groove design for a very low excess loss. We propose new approaches for modifying the shape of the grooves and the arrayed waveguides and optimize the shape modifications for 1.5%-/spl Delta/ waveguides. By employing this modified groove design, we greatly reduced the groove excess loss from 1.9 to 0.4 dB in the 1.5%-/spl Delta/ athermal AWG.

Athermal arrayed-waveguide grating multi/demultiplexers composed of TiO/sub 2/--SiO/sub 2/ waveguides on Si

We have successfully demonstrated a novel athermal arrayed-waveguide grating (AWG), which is composed of highly TiO/sub 2/-doped SiO/sub 2/ glass rib waveguides on a silicon substrate. We found that the wavelength temperature coefficients of the athermal AWG depend not only on the TiO/sub 2/ concentration but also on the annealing temperature after fabrication. We obtained a center wavelength temperature coefficient of 0.7 pm//spl deg/C at a TiO/sub 2/ concentration of 66 mol% and an annealing temperature of 900/spl deg/C.

Extremely low-loss 1.5%- 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.