Bo Pedersen

1800 Gb/s transmission of one hundred and eighty 10 Gb/s WDM channels over 7000 km using the full EDFA C-band

One hundred and eighty 10 Gb/s WDM channels were transmitted over 7000 km in 43 nm of optical bandwidth with a maximum spectral efficiency of 0.4 (bits/s)/Hz. Error free performance was measured for all channels using an advanced error correcting code.

640 Gb/s transmission of sixty-four 10 Gb/s WDM channels over 7200 km with 0.33 (bits/s)/Hz spectral efficiency

Sixty-four 10 gb/s WDM channels were transmitted over 7200 km is a spectral bandwidth of 15.1 nm for a spectral efficiency of 0.33 (bits/s)Hz. Error free operation was achieved for all channels.

Performance improvement in high capacity, ultra-long distance, WDM systems using forward error correction codes

We present a performance study of a forward error correction (FEC) code using theoretical models, Monte-Carlo computer simulations, and a long-haul WDM transmission experiment. With a 14% redundancy code, the Q-factor was increased by 6.2 dB for both linear and non-linear impairments.

Assessment of the allergic reaction in seasonal rhinitis: acoustic rhinometry is a sensitive and objective method

Background Seasonal allergic rhinitis constitutes an excellent in vivo model of an allergic mucosal inflammatory reaction. This offers the opportunity of studying the fundamentals of allergic inflammation in addition to improvement of knowledge on the basal pathophysiological mechanisms of the disease. So far, monitoring methods of disease activity and treatment efficacy have mainly been based upon subjective assessments, illustrating the impact of introducing reliable objective methods.

Erbium doped fibre amplifier: efficient pumping at 807 nm

Abstract Two new pump configurations for pumping Er 3+ -doped fibres in the 807 nm pump band are presented and examined. An extra gain of 3.3 dB is obtained by pumping from both ends instead of pumping just from the input end. The noise figure for the investigated configurations is shown to have a minimum with regard to signal input power at - 17 dBm.

Optimum placement of a fiber-optical amplifier in high-bit-rate direct-detection systems.

Six system configurations of an erbium-doped fiber amplifier are analyzed accurately. Amplifier placement in the middle of the transmission link is shown to be optimum.

Optimum placement of filters in 1300 nm Nd-fibre amplifiers

Abstract A general procedure for determining the optimum placement of filters in Nd 3+ -doped ZBLANP fibres is presented. Extra gain of 5 dB per filter is predicted for the first four filters, yielding 20 dB of gain with 125 mW of pump power using three filters.

Gain variations for an erbium doped fiber amplifier in a temperature-range from 45 K to 320 K

The erbium doped fiber amplifier (EDFA) has emerged as a key element for long distance optical communication systems because of high gain, low noise, polarization insensitivity and low coupling losses. The temperature dependent gain of the amplifier in a small range around room temperatures is interesting for practical applications of the EDFA under normal operation [1,2]. Knowledge about the temperature dependence in a large temperature range is important for the basic understanding of the erbium ion and may yield to new applications for the Er-doped fiber. Earlier reports have shown gain variations, measured in a temperature range from approximately 233 Κ to 358 Κ for the pump wavelengths at 0.98 μπι [1] and 1.48μπι [2]. Gain measurements at cryogenic temperatures have been presented at the boiling point of liquid nitrogen (77 K), when pumped at 0.514 μπι [3], 0.8 μπι [4] and 1.48 μπι [5]. The results show an increased gain at this particular temperature compared to the gain around room temperature. This letter reports continuous gain measurements in a large range from 45 K to 320 K, showing that the gain dependence on the temperature is divided in four different linear sections, with significantly different gain to temperature coefficients in dB/K.

Analysis of erbium-doped fiber amplifiers pumped at 800 nm

Abstract The performance and efficiency of erbium-doped fibers pumped in the 800-nm band has been analyzed using a quantitative amplifier model. Both a silica and a fluorophosphate host were investigated. The analysis showed that under optimized conditions the fluorophosphate is superior to the silica with higher gain and up to 60% higher quantum conversion efficiency. Only with respect to noise figure is the fluorophosphate poorer because of the shorter lifetime of the metastable state.

Silica waveguide integrated optical isolator

An integrated optical waveguide isolator based on adiabatic polarization splitters in the silica- on-silicon technology and non-reciprocal elements are proposed and investigated with an accurate Finite Difference Beam Propagation Method. Improvements of noise figure of an erbium-doped fiber amplifier by using this type of isolator are calculated and discussed.