Photonic devices - Nonlinear optics

On-chip CMOS compatible reconfigurable optical delay line with separate carrier tuning for microwave photonic signal processing

by Maurizio Burla

Optics Express, Vol. 19, Issue 22, pp. 21475-21484 (2011)
http://dx.doi.org/10.1364/OE.19.021475

We report, for the first time, an integrated photonic signal processor consisting of a reconfigurable optical delay... more We report, for the first time, an integrated photonic signal processor consisting of a reconfigurable optical delay line (ODL) with a separate carrier tuning (SCT) unit and an optical sideband filter on a single CMOS compatible photonic chip. The processing functionalities are carried out with optical ring resonators as building blocks. We show that the integrated approach together with the use of SCT technique allows the implementation of a wideband, fully-tunable ODL with reduced complexity. To highlight the functionalities of the processor, we demonstrate a reconfigurable microwave photonic filter where the ODL has been configured in a bandwidth over 1 GHz.

© 2011 OSA

High speed liquid crystal over silicon display based on the flexoelectro-optic effect

by Jing Chen

Jing Chen, Stephen M. Morris, Timothy D. Wilkinson*, Jon P. Freeman, and
Harry J. Coles*

Centre of Molecular Materials for Photonics and Electronics, Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom

One of the key technologies to evolve in the displays market in recent years is liquid crystal over silicon (LCOS)... more One of the key technologies to evolve in the displays market in recent years is liquid crystal over silicon (LCOS) microdisplays. Traditional LCOS devices and applications such as rear projection televisions, have been based on intensity modulation electro-optical effects, however, recent developments have shown that multi-level phase modulation from these devices is extremely sought after for applications such as holographic projectors, optical correlators and adaptive optics. Here, we propose alternative device geometry based on the flexoelectric-optic effect in a chiral nematic liquid crystal. This device is capable of delivering a multilevel phase shift at response times less than 100 μsec which has been verified by phase shift interferometry using an LCOS test device. The flexoelectric on silicon device, due to its remarkable characteristics, enables the next generation of holographic devices to be realized.

© 2009 Optical Society of America

Reversible color switching from blue to red in a polymer stabilized chiral

by Jing Chen

Jing Chen, Stephen M. Morris, Timothy D. Wilkinson, and Harry J. Coles

Centre of Molecular Materials for Photonics and Electronics, Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 J.J. Thomson Avenue, Cambridge CB3 0FA, United Kingdom 

(Received 6 June 2007; accepted 1 September 2007; published online 20 September 2007)

In this letter, the authors demonstrate reversible color switching from blue to red in polymer stabilized chiral... more In this letter, the authors demonstrate reversible color switching from blue to red in polymer stabilized chiral nematic liquid crystals when viewed at oblique angles. A series of unusual colored scattering states, different from those noted in polymer-free samples, was observed in cells that had been prepared using a technique of cooling the sample from the isotropic phase in the presence of a low frequency
80 Hz applied electric field and then photopolymerizing the sample on both sides of the cell. This process “freezes-in” a texture whereby the helix axis lies preferentially in the plane
of the cell.

© 2007 American Institute of Physics.
[DOI: 10.1063/1.2789290]

The third-order nonlinear optical properties of novel styryl dyes

by Abdullah Asiri