Liquid crystal waveguide technologies for a new generation of low power photonic integrated circuits Antonio d’Alessandro* a,b , Luca Martini a , Luca Civita a , Romeo Beccherelli b , Rita Asquini a,b a Dept. of Information, Electronic and Telecommunication Engineering, Sapienza Univ. of Rome, via Eudossiana, 18 – Rome, Italy 00184; b Consiglio Nazionale delle Ricerche – Istituto per la Microelettronica e Microsistemi (CNR-IMM) Via del Fosso del Cavaliere, 100 - 00133 Rome - Italy ABSTRACT In this paper we show two approaches to fabricate photonic channels on different substrate technology platforms, in particular silicon and polydimethylsiloxane (PDMS), for flexible photonic integrated circuits. The electro-optic effect and nonlinear optical properties of liquid crystals (LC) allow the realization of low cost and low energy consumption optoelectronic devices operating at both visible and near-infrared wavelengths. High extinction ratio and large tuning range guided wave devices will be presented to be used for both optofluidic and datacom applications, in which both low realization costs and low power consumption are key features. In particular we will show our recent results on polarization independent light propagation in waveguides whose core consists of LC infiltrated in PDMS channels (LC:PDMS waveguides) fully compatible with optofluidic and lab-on-chip microsystems. Keywords: liquid crystals, optical waveguides, optofluidics, electro-optical devices, nonlinear optics, all-optical devices, electro-optic effects, integrated optics, optoelectronic devices. 1. INTRODUCTION The recent large development of data centers, which are considered the backbone of the new economy, and the ever increasing internet traffic intensity require higher and higher level of energy to be sustained. The energy required includes both a higher level demand of resources and above all poses a serious environmental problem related to the dissipated power. It has been estimated that the overall energy consumption increases by approximately 5% per annum in the period 2009-2017 for a telecommunication network 1 . Although many companies are adopting data center best practices to reduce power consumption, on the research side many efforts are oriented to look for new technologies, which are able to substantially minimize both energy system requirements and power dissipation. Such efforts are also related to interconnections at different levels, rack-to-rack, board-to-board and even at level of chip-to-chip. A strong limitation for a further development of computer networks and also data centers is due to the high loss of metal interconnections 2 . Photonic components can be a solution simply because power requirements are in general significantly lower than the electrical counterparts. This adds up to massive data capacity and transparency. Recent advances in silicon photonics made possible significant progress in off-chip communication bandwidth. However, this comes at the cost of some additional power consumption in the electronics, due to added processing and buffering that can be hardly avoided 3 . Nevertheless the current photonic systems make use of current driven lasers whose power requirements is still quite high and need to be reduced especially for short distances connections. The power consumptions for the optical interconnections are in fact related mainly to laser diodes which cannot be turned ON and OFF at a speed enough to save power. When distance are longer that 1-5 m optical interconnections costs are compensated by their higher power efficiency than the efficiency of metal cables 4 . It is therefore important to look also for new technological platforms to obtain the best benefits from using optical interconnections both in datacom and other interesting new application fields such as those related to optofluidic devices, characterized by the possibility to change their optical properties by manipulating fluids. *antonio.dalessandro@uniroma1.it; phone +39 06 44585459; http://webdiet.diet.uniroma1.it/personale/dalessandro/ Invited Paper Emerging Liquid Crystal Technologies X, edited by Liang-Chy Chien, Harry J. Coles, Hirotsugu Kikuchi, Ivan I. Smalyukh, Proc. of SPIE Vol. 9384, 93840L · © 2015 SPIE · CCC code: 0277-786X/15/$18 · doi: 10.1117/12.2078891 Proc. of SPIE Vol. 9384 93840L-1 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 03/16/2015 Terms of Use: http://spiedl.org/terms