Packaging Technology for Ultra-Small Variable Optical Attenuator Multiplexer (V-AWG) With Multichip PLC Integration Structure Using Chip-Scale-Package PD Array

We have developed an ultra-small 16-channel variable optical attenuator (VOA) multiplexer (V-AWG) with excellent optical performance by using multichip planar lightwave circuit (PLC) integration technology. The insertion loss is 3.2 dB, and the polarization-dependent loss (PDL) at 25 dB attenuation is less than 0.3 dB. The module size is 90 mmtimes55 mmtimes14 mm. We describe our concept and developed techniques as regards to the design, fabrication, and packaging of the module, focusing particularly on a chip-scale-packaged monitor photodiode array (CSP-PD) that we developed as a key component of our technique

I. Introduction

Rapid development in optical fiber network systems has been driving an increasing demand for integrated optical components with rather complicated functions, where multiple passive and active optical functions should be combined together with their control electronics in a small module or a subsystem package. The variable optical attenuator (VOA) multiplexer (V-AWG) [1]–[5] shown in Fig. 1 is one such module, and it is being developed with some urgency to allow the cost-effective construction of high-performance reconfigurable optical add/drop multiplexing (ROADM) nodes. These demands have led to new requirements as regards to module fabrication technology. We now need to find cost-effective ways to provide such complicated modules for small-lot and custom applications with a short time to market, in addition to good performance and reliability. Fig. 1.

Typical configuration of a V-AWG module in a ROADM node. The V-AWG module function is shown by the gray square and consists of MUX/DEMUX AWGs, VOAs, power taps, and monitor photodiodes.