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© Trinity College Dublin 2010. All rights reserved.

Further information:

Brendan Ring Commercialisation Manager  

E: Brendan.Ring@tcd.ie T: +353 (0)1 896 3088

Unique Optical Signal to NoiseRatio Measurement Device

Trinity

College

Dublin

more

Centre for Research on

Adaptive Nanostructures

and Nanodevices

Basic overviewThis novel method for measuring the Optical signal to noise ratio

(OSNR) in optical networks does not require any prior knowledge

of the signal or the noise. Our dual interferometer, fiberized scheme

overcomes limitations of previous single interferometer-based

systems in which the noise must be turned off to determine the signal

value, something that is very difficult to do in a functioning network.

Applications

OSNR is a key measure of the health of optical

networks; particularly those used for optical

telecommunications, and is a key parameter for future

high speed and transparent optical networks.

M Our dual interferometer OSNR scheme will

be useful for monitoring optical signals in

telecommunications systems operating at 10 G,

40 G and 100 G.

M It can be used to both monitor amplitude and phase

modulated formats.

What problem does it

solve/advantages?

Optical noise from erbium-doped fiber amplifiers is

a major impairment to optical network functioning intelecommunications. When the network becomes more

complex with more complicated signal routes and more

densely spaced communication channels, in-band

OSNR monitoring becomes an absolute necessity.

Globally, there are various methods being proposed

to address the in-band OSNR monitoring issue. They

generally involve complex and expensive polarization

controller units or optical spectrum analyzer devices.

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Our dual interferometer OSNR provides a cost-effective

and robust solution to the in-band OSNR monitoring

problem. Any impairments to the signal incurred from the

network such as chromatic dispersion, polarization mode

dispersion, additional filtering, etc, will not influence the

function of the module. In particular, the polarization of

the noise will not influence the module function compared

to competing modules whereas in current fault testing

equipment single interferometer based schemes the noise

must be turned off to determine the signal autocorrelation.

Our dual interferometer OSNR scheme overcomes

limitations of its competitors:

M The fiberized scheme uses dual interferometers to

measure OSNR without the need to turn off the noise.

M Measurements have been made on 10G NRZ OOK

signals, 5G and 2G with no change in performance at

the lower modulation rates. This can be easily extended

to 40 G and 100 G through simple changes to the

delays in the two interferometers.

M Scheme has been shown to be immune to signal

polarization, noise polarization and signal dispersion.

M Measurement range from below 10 to 30 dB and

accuracy of +/- 0.5dB.

M Initial studies show that the scheme can work for phase

modulated signals. However the range is less than

for amplitude modulation and further studies are now

required.

Unique Optical Signal to Noise Ratio

Measurement Device

Schematic of the OSNR monitoring system for

operation with high speed signals

Picture of the prototype

OSNR monitor built in

TCD

Schematic of the OSNR dual fiber interferometer

CRANN located in Trinity College Dublin is Ireland’s flagship nano research institute. We are focused on producing and

commercialising world-class research and are deeply integrated with industry. We have ongoing collaborations with large

multinationals and small to medium local enterprise.

The 250 strong research team is involved right across the spectrum from materials, magnetics, energy and drug development

right thorough to product development of medical devices, sensors and integrated circuits. This is facilitated by our state of

the art Advanced Microscopy Laboratory www.crann.tcd.ie/index/Facilities/AdvancedMicroscopyLaboratory in conjunction

with our cleanroom, optics labs and business incubation facilities.

More detailed description of the technology

and Patent StatusFollowing the patenting, a publication has appeared

in the journal Optics Express. The article can be

downloaded free of charge at http://www.opticsinfobase.org/ 

view_article.cfm?gotourl=http%3A%2F%2Fwww.opticsinfobase.

org%2FDi rec tPDFAccess%2FEBF62209-F78C-F373-

D6FA99B9FA548756_195458.pdf%3Fda%3D1%26id%3D195458

%26seq%3D0%26mobile%3Dno&org

Our OSNR technology was filed with the European patent

office in Oct. 09, the filing number is WG01-194-01.

Principal Inventor

Prof. John F Donegan

Prof. John F Donegan is a Princpal Investigator in CRANN and

Head of the School of Physics at Trinity College. His research

deals with the interaction of light with matter. He has a diverse

range of interests from widely tunable semiconductor lasers, two-

photon absorption photodetectors, fluorescent nanowire formation,

photonic molecules to quantum dots interactions with human cells.

Across all these areas, the goal is the control and understanding of

physical processes through coupling of light to photonic structures.

He has published more than 200 papers on research into optical

condensed matter research and is co-author of 12 patent applications.

This is a fast expanding area in a growing, high value market. Our prototype monitor is

available for testing under network conditions. The technology is available for licence

to telecommunications equipment suppliers or is also available as a standalone device

suitable for tech start up.

The opportunity

www.crann.tcd.ie