Łukasz Chorchos

Influence of four-wave mixing in short- and medium-range 1310 nm dense wavelength division multiplexing systems.

In this paper, we demonstrate a comprehensive analysis of the impact of four-wave mixing (FWM) on the quality of transmission in short- and medium-range dense wavelength division multiplexing (DWDM) systems in the 1310 nm wavelength domain. The presented analysis proves that, for the system with uniform power per channel assignment, setting proper input channel power can substantially reduce the influence of the FWM effect on bit error rate in low channel spaced short-range systems, despite the position of the DWDM grid around the zero-dispersion wavelength. Simulations and experimental analysis of the possibility of FWM suppression have been provided. The power penalty measurements show that the influence of FWM on system performance may be as low as 0.3 dB with reasonable input power (i.e., -11  dBm per channel), making possible the transmission of data by fiber over distances of 25 km. Finally, we demonstrate that, for channel spacing as low as 120 GHz, error-free transmission in the 1310 nm wavelength domain is possible, despite high efficiency of FWM generation. The results prove that utilization of the 1310 nm wavelength domain in a system with low channel spacing, i.e., with better bandwidth allocation, is an interesting solution for data storage and processing center applications.

Relative intensity noise of single- and multi-mode 850 nm vertical-cavity surface-emitting lasers

In this paper we present the results of relative intensity noise (RIN) measurements for single- and multi mode 850 nm vertical cavity surface emitting lasers (VCSEL). The method applied for the RIN measurements is based on an electrical spectrum measurement of a biased and unmodulated laser. The conducted measurements show that the RIN values of around 150 dB/Hz can be expected from MM and SM VCSELs.

100G Flexible IM-DD 850 nm VCSEL Transceiver with Fractional Bit Rate Using Eight-Dimensional PAM

We demonstrate a novel optical transceiver scheme with a net flexible bit rate up to 100Gbit/s with 5 Gbit/s granularity, using an eight-dimensional modulation format family, and investigate its performance on capacity, reach, and power tolerance.

SSMF 1310nm dispersion characteristic influence on the 400 Gbit/s and 1000 Gbit/s ethernet physical layer design

In this paper, influence of the standard single mode fibre (SSMF) dispersion characteristic on the multi-wavelength 1310 nm wavelength domain 400 and 1000 Gbit/s transmission is investigated. The four-wave mixing (FWM) effect and residual chromatic dispersion can significantly limit the system performance. Limitations due to the FWM effect are studied for various types of SSMF fibre. Suppression of the FWM effect will require the channel spacing of at least 1.4 nm. The FWM effect can be suppressed in fibres with the large core area, allowing much higher input powers or narrower channel spacing. Further limitations due to the residual chromatic dispersion are evaluated and the capacity and transmission trade-off’s are studies in detail. It is shown that, the chromatic dispersion related limitations are pronounced for the wavelength channel allocation that is favorable from the manufacturing and installation point of view. These limitations can be omitted by the alignment of the wavelength channels to the zero-dispersion wavelength band and its management in the fibre infrastructure. The line rate of 40 Gbit/s outperforms the 50 Gbit/s taking into account the transmission capacity and distance. The presented results support development of 400 Gbit/s and 1000 Gbit/s Ethernet physical layer.

High speed 850 nm single mode and multi mode VCSEL transmission over multimode fiber

In this paper, we evaluate the transmission throughput/range limits for multi mode and single mode 850 nm vertical cavity surface emitting lasers. Transmission experiments in the various configurations like fibre length are performed. We utilize the most basic modulation format as amplitude shift keying without any form of digital signal pre and post processing. Operation up to 50 Gbit/s below 7% FEC limit was achieved for both multi and single mode VCSEL. Experiments showed that SM VCSEL outperforms MM VCSEL in both fields: transmission distances and high speed performance operating error free at 25 Gbit/s up to 200 meters and achieving two orders of magnitude lower BER at 50 Gbit/s (3.7*10-5 for SM comparing to 3.1*10 -3 for MM).

Reconfigurable remote access unit for W-band Radio-over-Fiber transmission

There is a growing demand for cost-effective radio over fiber transmission techniques. In this paper, we propose and realize the reconfigurable remote access unit for radio over fiber transmission. The reconfigurable unit is build from the tunable filter and laser as well as remote controller. Successful generation of the mm wave signals up to 83 GHz with transmission at 1550 nm is demonstrated.

On high speed transmission with the 850nm VCSELs

One of the key research challenges is development of energy efficient high bit rate data interconnects. The most promising solutions are based on 850 nm vertical cavity surface emitting lasers (VCSEL) and multi mode fibre (MMF). In this paper options to realize energy efficient 850 nm data interconnects are discussed and evaluated.

Performance comparison of the 1310nm optical amplifiers

One of the key optical transmission components are optical amplifiers. In this paper studies on the amplification properties of the 1310 nm optical amplifiers are presented. The evaluated optical amplifiers are: semiconductor optical amplifier (SOA) and praseodymium doped fibre amplifier (PDFA). The study is aimed to the dynamic operation in single- and multi- wavelength domain with the high rate signals namely 25 Gbit/s. The maximum obtained gain was 25.0 dB for SOA and 20.9 dB for PDFA. For the SOAs the minimum achieved value of the receiver sensitivity was -11.5 dBm for single channel and -11.5 dBm for DWDM case when for PDFA those values were -11.0 dBm and -10.9 respectively. The main advantage of the PDFA in comparison to the measured SOAs is higher saturation power.

RIN measurements of the 850nm VCSELs

In this paper, the relative intensity noise (RIN) measurements studies of multimode 850nm vertical cavity surface emitting lasers are presented. The used method is based on the RF spectrum measurement of a biased and unmodulated laser. Further a method based on the oscilloscope measurements is applied. The results obtained for both methods are comparable and differ less than 2 dB. The obtained RINs were in the range from -143.87 to -139.45 dB/Hz for various VCSEL biases.

Cost-effective tunable 1310nm DWDM transmitter

The growing demand for higher data rate transmissions in local and metropolitan area networks is main reason of developing effective and inexpensive transmission systems. In this paper, study about the possibility to realize 1310 nm tunable DWDM transmitter using commercially available low-cost DFB lasers is presented. Extensive DFB lasers characterization has been performed which led to establish relationships between laser current, operational temperature, emitted wavelength and power. An algorithm to find the laser settings for a desired wavelength grid has been proposed and tested. Generation of the 1310nm DWDM channels with frequency spacing between 120 and 240GHz has been demonstrated.