Wavelength Routing Optical Switch

Wavelength Routing Optical Switch

1.Research background

In the next generation optical network, to avoid
•congested lines
•fault lines
signal path optimization is performed in wavelength domain and the signal path is constantly changing.
⇒optical switches are essential for constructing the nodes

Fig.1 Wavelength routing on WDM networks

Fig.2 Wavelenth selective swicth

Research objective

Investigate on large-scale free-space wavelength selective switch (WSS) with high functionality。

2.LCOS type WSS

Sub-topic 1

Conventional LCOS type WSS requires bulky optical components leading to complex configuration
⇒Large size, high assembly cost, low reliability

Use multi-layered arrayed waveguide grating (AWG) for spectrometric optics
⇒bulky diffraction grating and beam shaping optics become unnecessary
⇒simple configuration

Fig.3 LCOSS-WSS using multi-layed AWG with polarization compensation

Sub-topic 2

Producing a practical AWG is difficult due to its phase error caused by waveguide layers and polarization modes
⇒high loss and PDL

Compensate phase error by phase modulation using LCOS
⇒low loss and low PDL

Fig.4 Swicthing operation of proposed WSS

Sub-topic 3

LCOS is very costly
Propose a WSS configuration that enables
•phase error compensation
•swithcing operation
on a single LCOS
⇒low cost and small size

Fig.5 Image layout on LCOS

スイッチング特性

Fig.6 Multi-arrayed AWG

Fig.7 Transmission spectrum of WSS showing switching operation a) Without polarization error compensation b) Polarization error compensated

resalt of a 40Gbit/s signal transmission experiment

Fig.8 40Gbps signa; transmission experiment

3.MEMS type WSS

Sub-topic 4

Spectrum ripples are generated when performing flexible grid operation using a MEMS type WSS
⇒impossible to realize MEMS type WSS with a flexible grid
Introduce slot structures on the mirror surface to equalize the reflection loss
⇒ripple suppression
⇒flexible grid operation becomes possible

Fig.9 MEMS-WSS

スペクトル計算

Fig.10 Transmission spectrum calculation in the case of a) large spot size and b) small spot size. N is the number of slot on a mirror

4.Research achievements

(a)．Journals
[1]	K. Sorimoto, K. Kintaka, H. Kawashima, M. Mori, T. Hasama, H. Ishikawa, H. Tsuda, and H. Uetsuka, “Fast Aberration-Correcting Algorithm for an SLM-based Optical Switch,” IEICE Electron. Express Vol. 7, No. 23, pp. 1728-1734(2010).
[2]	[2] K. Sorimoto, K. Kintaka, H. Kawashima, M. Mori, T. Hasama, H. Ishikawa, H. Tsuda, and H. Uetsuka, “Phase Error Compensation for Multilayered AWG in LCOS-based WSS,” IEICE Electron. Express, Vol. 8, No. 24, pp.2054-2060, Dec. 25 (2011).
[3]	Keisuke Sorimoto, Hitoshi Kawashima, Masahiko Mori, Toshifumi Hasama, Hiroshi Ishikawa, Hiroyuki Tsuda, and Hisato Uetsuka, “MEMS mirror with slot structures suitable for flexible-grid WSS,” IEICE Electron. Express, Vol. 10, No. 3, pp. 20120924 (2013). DOI: 10.1587/elex.10.20120924.
[4]	Keisuke Sorimoto, Ken Tanizawa, Hisato Uetsuka, Hitoshi Kawashima, Masahiko Mori, Toshifumi Hasama, Hiroshi Ishikawa, and Hiroyuki Tsuda “Compact and Phase-Error-Robust Multilayered AWG-based Wavelength Selective Switch Driven by a Single LCOS,” Optics Express Vol. 21, Iss. 14, pp. 17131-17149 (2013).

(b)．International conferences
[5]	K. Sorimoto, K. Kintaka, H. Kawashima, M. Mori, T. Hasama, H. Ishikawa, H. Tsuda, and H. Uetsuka, “1×6 Multicasting Operation in an LCOS-and-AWG-based Wavelength Selective Switch,” 1st International Symposium on Access Spaces (IEEE-ISAS 2011), GS3-B-3, Yokohama, Japan, Jun. 18 (2011).
[6]	K. Sorimoto, H. Tsuda, H. Ishikawa, T. Hasama, H. Kawashima, K. Kintaka, M. Mori, and H. Uetsuka “Polarization Insensitive Wavelength Selective Switch Using LCOSs and Monolithically Integrated Multi-layered AWG,” 15th Optoelectronics and Communications Conference (OECC 2010),6E2-4, July 5-9, Sapporo, Japan (2010).
[7]	K. Sorimoto, H. Tsuda, H. Ishikawa, T. Hasama, H. Kawashima, K. Kintaka, M. Mori, and H. Uetsuka, “Demonstration of a Wavelength Selective Switch Using an LCOS and a Stacked Arrayed Waveguide Grating,” 35th European Conference and Exhibition on Optical Communication (ECOC) 2009, P. 2.04, Sep. 20-24, Vienna, Austria, (2009).
[8]	K. Sorimoto, H. Tsuda, H. Ishikawa, T. Hasama, H. Kawashima, K. Kintaka, M. Mori, H. Uetsuka, “Design of a wavelength selective switch using an LCOS and a multi-stacked AWG fabricated on wedge-shaped substrates,” International Topical Meeting on Information Photonics (IP2008), 3-P4, Nov. 16-20, Hyogo, Japan (2008).
[9]	K. Sorimoto, H. Tsuda, H. Ishikawa, T. Hasama, H. Kawashima, K. Kintaka, M. Mori, H. Uetsuka, “A Compact High-Port-Count Wavelength Selective Switch Using LCOSs and a Multi-Stacked AWG,” The 21st Annual Meeting of the IEEE Lasers & Electro-Optics Society 2008, TuCC2, Nov. 11, Newport Beach, USA, (2008).