[OPTICAL REVIEW Vol. 11, No. 2 (2004) 132-139]
© 2004 The Optical Society of Japan

A Pixelized Variable Optical Attenuator Using Liquid Crystal on Silicon Technology for Tunable Filters

Masafumi IDE*, Akira SUGURO, Yasushi HOSAKA, Atsushi KATSUNUMA1, Kouzou TAKAHASHI2 and Atsushi SHIRAISHI3

Micro-Human-Tech Research and Development Division, Citizen Watch Co., Ltd., 840, Shimotomi, Tokorozawa, Saitama 359-8511, Japan
1Optical Design Department, Sagamihara Plant, Nikon Corp., 1-10-1, Asamizodai, Sagamihara, Kanagawa 228-0828, Japan
2Customized Products Division, Nikon Corp., 1-6-3, Nishi-ohi, Shinagawa-ku, Tokyo 140-8601, Japan
3Liquid Crystal Display Device Division, Citizen Watch Co., Ltd., 6-1-12, Tanashicho, Nishi-Tokyo, Tokyo 188-8511, Japan

(Received December 19, 2003; Accepted March 2, 2004)

We apply liquid crystal on silicon (LCOS) in 0.8-μm standard complementary metal-oxide semiconductor (CMOS) technology to demonstrate a low-cost, high-performance pixelized liquid crystal variable optical attenuator (VOA) with pulse width modulation. We then build a prototype tunable filter by using this VOA along with a grating in the Littrow configuration. With the application of 5-V pulse width modulation, the proposed VOA achieves a 5.6-dB insertion loss, a dynamic range of more than 20 dB, a 50-GHz channel spacing capability, and a polarization-dependent loss (PDL) of less than 0.6 dB at 15-dB attenuation. Our VOA is suitable for applications such as dynamic channel gain equalizers, channel-blocking filters, sub-components of re-configurable add-drop modules, and wavelength selectors.

Key words: WDM (wavelength division multiplexing), electro-optic response, fiber optics, liquid crystals, tunable filters, gratings

*E-mail address: ide@citizen.co.jp