An Opto-VLSI-based reconfigurable optical adddrop multiplexer employing an off-axis 4-f imaging system

Mingya Shen,Kamal Alameh,Selam Ahderom,Feng Xiao

doi:10.1364/oe.17.014015

Abstract

A novel reconfigurable optical add-drop multiplexer (ROADM) structure is proposed and demonstrated experimentally. The ROADM structure employs two arrayed waveguide gratings (AWGs), an array of optical fiber pairs, an array of 4-f imaging microlenses that are offset in relation to the axis of symmetry of the fiber pairs, and a reconfigurable Opto-VLSI processor that switches various wavelength channels between the fiber pairs to achieve add or drop multiplexing. Experimental results are shown, which demonstrate the principle of add/drop multiplexing with crosstalk of less than -27dB and insertion loss of less than 8dB over the Cband for drop and through operation modes.

Highlights

Reconfigurable optical add-drop multiplexers (ROADMs) are key devices in dynamic wavelength-division multiplexing (WDM) optical communication networks
ROADM structures based on micro-electro-mechanical systems (MEMS) have been reported [3], where small mirrors are deformed or reoriented using electrostatic forces to steer optical beams and couple them into different output fiber ports
Dropped wavelengths are multiplexed via the second arrayed waveguide grating (AWG2) and routed to the drop port through a circulator, while the added wavelengths that are launched at the addport propagate along different AWG2 paths and in opposite directions to the dropped wavelengths, where they are steered by the Opto-VLSI processor, coupled to the upper fibers and multiplexed via AWG1 to reach the thru port

Summary

Introduction

Reconfigurable optical add-drop multiplexers (ROADMs) are key devices in dynamic wavelength-division multiplexing (WDM) optical communication networks. The use of Opto-VLSI processors for realizing add/drop multiplexing has attracted research attention in recent years. The Opto-VLSI processor is based on the mature motionless liquid crystal on silicon technology and is advantageous because it enables add/drop multiplexing of a large number of wavelength channels through computergenerated phase holograms [5], [6]. A ROADM structure based on the use of an Opto-VLSI processor and a custom-made angled fiber-pair array has recently been demonstrated [7]. By partitioning the Opto-VLSI processor into pixel blocks and driving each pixel block with a “drop” or a “thru (i.e. through)” steering phase hologram, optical switching between each optical fiber pair can be realized, leading to optical add/drop multiplexing. The proposed ROADM structure has a large bandwidth covering the C-band wavelength signals and moderate insertion loss and crosstalk and can be constructed by integrating off-the-shelf optical components

Opto-VLSI-based ROADM – structure and principle

Experiment and results

Conclusion