Experimental verification of four wave mixing efficiency characteristics in a few mode fibre

We introduce two techniques to measure the efficiency of inter mode FWM with respect to intra mode FWM. The first technique allows an estimation of the additional FWM penalty for any given system; the second isolates the contribution of each mode. Measurements are compared to an analytical model showing the FWM signal increases by ∼2dB with inter mode phase matching

Phase-conjugated pilots for fibre nonlinearity compensation in CO-OFDM transmission

We experimentally demonstrate a novel fibre nonlinearity compensation technique for CO-OFDM based on phase-conjugated pilots (PCPs), showing that, by varying the PCP overhead a performance improvement up to 4 dB can be achieved allowing highly flexible adaptation to link characteristics

High spectral efficiency transmission emulation for non-linear transmission performance estimation for high order modulation formats

We demonstrate a simple method to experimentally evaluate nonlinear transmission performance of high order modulation formats using a low number of channels and channel-like ASE. We verify it's behaviour is consistent with the AWGN model of transmission

Experimental comparison of coherent polarization-switched QPSK to polarization-multiplexed QPSK for 10 x 100 km WDM transmission

Polarization-switched quadrature phase-shift keying has been demonstrated experimentally at 40.5Gb/s with a coherent receiver and digital signal processing. Compared to polarization-multiplexed QPSK at the same bit rate, its back-to-back sensitivity at 10-3 bit-error-ratio shows 0.9dB improvement, and it tolerates about 1.6dB higher launch power for 10 × 100km, 50GHz-spaced WDM transmission allowing 1dB penalty in required optical-signal-to-noise ratio relative to back-to-back

First demonstration of 2μm data transmission in a low-loss hollow core photonic Bandgap fiber

The first demonstration of a hollow core photonic bandgap fiber suitable for high-rate data transmission at 2µm is presented. Using a custom built Thulium doped fiber amplifier, error-free 8Gbit/s transmission in an optically amplified data channel at 2008nm is reported for the first time

Space Division Multiplexing in Optical Fibres

Optical communications technology has made enormous and steady progress for several decades, providing the key resource in our increasingly information-driven society and economy. Much of this progress has been in finding innovative ways to increase the data carrying capacity of a single optical fibre. In this search, researchers have explored (and close to maximally exploited) every available degree of freedom, and even commercial systems now utilize multiplexing in time, wavelength, polarization, and phase to speed more information through the fibre infrastructure. Conspicuously, one potentially enormous source of improvement has however been left untapped in these systems: fibres can easily support hundreds of spatial modes, but today's commercial systems (single-mode or multi-mode) make no attempt to use these as parallel channels for independent signals.Comment: to appear in Nature Photonic

Som en hård spagetti som blivit kokt : Gymnasieelevers upplevelser av muntlig framställning

I dagens samhälle blir människans kommunikationsförmåga allt viktigare, så även i skolan. Därför är syftet med denna undersökning att ta reda på hur gymnasieelevers upplevelser av muntlig framställning ser ut. Jag avser även undersöka vilka faktorer som påverkar elevernas upplevelser och hur undervisningen kan organiseras så att elevernas upplevelser blir mer positiva. För att ta reda på detta har enkäter med öppna frågor använts. Efter en analys av enkätsvaren framkom att eleverna går att dela in i fyra kategorier. I den första är elevernas upplevelser positiva, i den andra känner de en stark nervositet som de dock kan kontrollera, i den tredje återfinns talängsliga elever och i den fjärde kategorin har eleverna varken positiva eller negativa upplevelser. Vidare visar elevernas svar att flickorna upplever mer ångest och oro i samband med muntlig framställning än pojkar och att framför allt eleverna på estet- och samhällsvetenskapsprogrammet är de som har de mest positiva upplevelserna. Andra saker som eleverna menar påverkar upplevelserna är publiken, klassrumsklimatet, hur väl förberedda de är, hur vana de är och vad de talar om. Läraren bör ta hänsyn till elevernas upplevelser och de faktorer som påverkar den när han eller hon organiserar undervisningen kring muntlig framställning. Dessutom förespråkar tidigare forskning en systematisk talträning och att eleverna får grunder i retorik och i den retoriska arbetsprocessen.

Future directions to realise ultra-high-bit-rate transmission systems

In this paper we examine two potential future directions for the realization of ultra-high bit rate transmission systems

First demonstration of 2 micron data transmission in a low-loss hollow core photonic bandgap fiber

The first demonstration of a hollow core photonic bandgap fiber suitable for high-rate data transmission at 2µm is presented. Using a custom built Thulium doped fiber amplifier, error-free 8Gbit/s transmission in an optically amplified data channel at 2008nm is reported for the first time