Strategies
Planar Lightwave Circuit Technologies for Photonic Network Innovation
Masao Kawachi
Managing Director of Technology Development Headquarters, NTT Electronics Corporation
This is my second contribution to the Strategies
column. Three years ago, I wrote “For Further Innovation,” as the Executive Director of NTT Science
and Core Technology Laboratory Group, an umbrella organization covering five laboratories including
the Photonics Laboratories and the Basic ResearchLaboratories. In that article, I pointed out that, inaddition to short-term NTT business contributions,those laboratories should perform advanced researchintended to bloom from 5 to 10 years later and evenallow work that might not bear fruit for 10 to 20years.
One example is research on silica-based opticalwaveguides on a planar silicon substrate. That work
was begun by the Basic Research Laboratories in theearly 1980s and then handed over to the Photonics
Laboratories. In the 1990s, research on integratedoptic arrayed-waveguide grating (AWG) multiplexers/demultiplexers bore fruit as NTT’s planar lightwave circuit (PLC) technology, which today has
become an important pillar in the optical component
business that supports commercial optical networks.
In my younger days in NTT Laboratories, I participated in the technological development of PLC, but
I was also involved in the founding (in 1987) of Photonic Integration Research, Inc. (PIRI), a joint venture company in Ohio, USA, and its sell-off (in 2000)
after it had succeeded. I was thus fortunate enough tosee basic research on silica-based optical waveguides
bloom into a range of PLC products on the worldmarket.
In 1993, a PLC division was established in NTT
Electronics Corporation (NEL). It has since growninto the largest of NEL’s business divisions. NEL wasseriously affected by the collapse of the Internet bubble in North America, which peaked in 2001, but now
PLC production is steadily increasing because of thetake-off in demand for FTTH (fiber to the home) inJapan and the recovery in demand for metropolitan
area network construction in North America. Thatsequence of events led to my transfer from NTT Lab-oratories to NEL in July 2005, and I contribute thissecond article as Managing Director of NEL’s Technology Development Headquarters.
NEL has three main PLC product groups.
1) AWG multi/demultiplexers, which led to thesuccess of PIRI in the context of the North
American boom in WDM (wavelength divisionmultiplexing) trunk network investment in thelate 1990s.
2) 1 × N optical splitters, which are indispensable
to the construction of FTTH networks by NTT
East and NTT West.
3) Thermo-optic switches, which are increasingly
important in the construction of metropolitan
area networks with reconfigurable optical
add/drop multiplexer functions.
Further efforts to improve PLC products andadvance PLC technology itself are not limited to NTT
Laboratories and NEL, but are now proceeding
through worldwide competition, in part created bythe sale of PIRI in 2000. In this way, PLC technology, to which NTT Laboratories has been a leading
contributor since the 1980s, can be expected to play
an increasingly major role in future photonic network
innovation throughout the world, including NTT’s
own NGN (next generation network) concept. NEL isdetermined to shoulder an important part of thatdevelopment effort in the future as a top PLC manufacturer.