Bo Foged Jørgensen

Analysis of polarization-insensitive optical phase conjugation in a dispersion-shifted fiber.

So-called polarization-insensitive optical phase conjugation with four-wave mixing in a dispersion-shifted fiber by the use of two orthogonally polarized pumps is analyzed theoretically. An inherent polarization dependence as a result of polarization-dependent cross talk, asymmetrical depletion of the two pumps and input signal, and polarization-sensitive phase conjugation is identified.

Long-distance transmission over standard fiber by use of mid-way phase conjugation

In this letter, we predict transmission over more than 6000 km using standard fiber with the application of mid-way phase-conjugation in a 1.55-/spl mu/m, 10-Gb/s IM/DD system with in-line amplifiers for the power penalty at BER=10/sup -9/, which is less than 6 dB; the system must operate with an average power into the fiber within the range of -5 to 5 dBm.<<ETX>>

Transmission performance through cascaded 1-nm arrayed waveguide multiplexers at 10 Gb/s

The transmission properties of cascaded arrayed waveguide multiplexers are examined in a recirculating loop experiment. We show that a cascade of 40 multiplexers each with 3-dB bandwidth of /spl sim/1 nm can be passed penalty-free at 10 Gb/s. Furthermore, we show that the allowable fluctuation of the center frequency for a 10 Gb/s signal is reduced to 24 GHz at bit-error rate (BER)=10/sup -9/ for a concatenation of 40 multiplexers.

Extinction ratio effect for high-speed optical fiber transmissions

In conventional optical transmissions, the extinction ratio is expected to be as high as possible in order to get better receiver sensitivity. But for high-speed long distance optical transmissions, the system performance is mainly dependent on the self-phase modulation (SPM) when the input optical power is sufficiently high. It is possible that a large improvement of the receiver sensitivity can be obtained by using an input signal with finite extinction ratio when the SPM takes effect. In this paper, the interaction of the fiber dispersion, SPM, prechirp and extinction ratio is investigated and the optimisation of system performance is implemented for a 10 Gbit/s long distance unrepeatered unregenerate optical transmissions.

Penalty-free transmission at 10 Gbit/s through 40 cascaded 1-nm arrayed waveguide multiplexers

Cascaded optical add-drop multiplexers (OADM) and optical cross connects (OXC) are key components in optical wavelength-division multiplex networks. OADMs with filtering of the passing signals and OXCs can be constructed by the use of wavelength-division multiplexers. Cascadability of multiplexers is therefore vital for the network performance. The actual transfer function of multiplexers is important, because the available end-to-end bandwidth between connected nodes in optical networks with cascades of OXCs and OADMs is given by the product of the transfer functions. In this paper, we demonstrate the cascadability of arrayed waveguide (AWG) multiplexers in a recirculating loop experiment at 10 Gbit/s and show that up to 40 multiplexers each with a 3-dB bandwidth of 1 nm and sharp roll-off characteristics can be passed penalty free.

Self-phase modulation induced transmission penalty reduction in a 5 Gbit/s FM/AM conversion system experiment over 205 km of standard fiber

The transmission penalty of a standard non-dispersion shifted fiber is experimentally demonstrated to be reduced by self-phase modulation due to the optical Kerr effect. A 2 dB reduction of transmission penalty is achieved in a 5 Gbit/s FM/AM conversion system experiment over 205 km of fiber. The origin of the transmission penalty change is discussed for clarification of the important interaction between modulation induced frequency chirp, self-phase modulation and group velocity dispersion in systems with high-power transmitters.<<ETX>>

An accurate model of optically preamplified receivers for arbitrary optical bandpass filter and arbitrary post-detection filter

An accurate model is presented for analyzing sensitivity and bit error rate performance of optically preamplified direct detection receivers suited for arbitrary input signal and arbitrary optical and electrical filters. The accuracy within 1 dB is verified experimentally.

Design of multi-core fiber patch panel for space division multiplexing implementations

ABSTRACT A multi-core fiber (MCF) patch panel was designed, allowing easy coupling of individual signals to and from a 7-core MCF. The device was characterized, measuring insertion loss and cross talk, finding highest insertion loss and lowest crosstalk at 1300 nm with values of 9.7 dB and -36.5 dB respectively, while at 1600 nm insertion loss drops to 4.8 dB and crosstalk increases to -24.1 dB. Two MCF splices between the fan-in module, the MCF, and the fan-out module are included in the characterization, and splicing parameters are discussed.

2 dB Reduction Of Transmission Penalty By Self - Phase Modulation In A 5 Gbit/s FM/AM Conversion System Experiment

The transmission penalty of a standard non-dispersion shifted fiber is experimentally demonstrated t o be reduced by SelfPhase Modulation due to the optical Kerr effect. A 2 dB reduction of transmission penalty is achieved in a 5 Gbit/s FM/AM conversion system experiment over 205 km of fiber. Introduction: The group velocity dispersion penalty of an optical communication system depends to some extent on the frequency chirp of the transmitted signal. One way to diminish the dispersion penalty in linear systems is by introducing a suitable chirp in the transmitted signal in order to obtain less dispersive pulse distortion [11-[41. In systems with high-power transmitters, the interaction between Self-phase Modulation (SPM) due to the optical Kerr effect and the group velocity dispersion has to be taken into account. In order to demonstrate the effect of this interaction, we report observation of transmission penalty dependence of Self-phase Modulation in a 205 km system experiment. The system employs a 5 Gbit/s frequency modulation (FM) to amplitude modulation (AM) conversion transmitter. A 2 dB reduction of transmission penalty with this modulation scheme is experimentally achieved by increasing the transmitter output power from +7 dBm to +14 dBm. Experimental Set-up: The experimental set-up is shown schematically in Fig. 1. A threeelectrode U4-shifted DFB laser with a 10 GHz FM-response bandwidth is used as transmitter [51. The laser is operated at a wavelength of 1548 nm and the linewidth is 2 MHz. The laser is modulated directly from the word generator with a 5 Gbit/s Pseudo Random Binary Sequence of length 27-l. The Continuos Phase Frequency Shift Keying (CP-FSK) signal of the transmitter laser is converted into an AM signal by the Mach-Zehnder interferometer (MZI). The differential delay of the MZI is z = 42 ps. An Erbium Doped Fiber (EDF) booster amplifier with a saturated output power of +15 dBm is used in the transmitter. The level of the transmitter output power is adjusted by an optical attenuator. The receiver is an optically preamplified pindetector receiver. The two stage EDF preamplifier is pumped at 980 nm. The fiber-to-fiber gain (including input and output connector insertion loss) is 34 dB and the corresponding noise figure is 4 dB. An optical Fabry-Perot filter with a 3 dB bandwidth of 20 GHz ensures that the noise in the receiver is dominated by signal-spontaneous emission beat noise. The filter is locked to the signal by an Automatic Frequency Control (AFC). The periodic frequency response of the Fabry-Perot filter is eliminated by a broadband optical bandpass filter with a bandwidth of 2.5 nm. A fourthorder Bessel filter with 3 dB cut-off frequency of 4 GHz is used as post-detection filter. The Bit Error Rate (BER) is measured with the error counter which is synchronized by a clock signal recovered by the receiver. 205 km of standard non-dispersion shifted optical fiber is inserted in between the transmitter and the receiver. This fiber length is chosen as a compromise between the available dynamic range of input power and the amount BMrmWW ! .... ~~ ..... .... ................... .. .... ~1 Figure 1. Experimental set-up.

Dispersion Limit Improvement Of FM/TM Signals By Self-phase Modulation

Abstract. Simulations of unrepeatered transmission of 10 Gbitls signals generated by frequency to intensity modulation conversion show an improvement of the dispersion limit on standard fiber due to self-phase modulation by up to a factor of 2.5. This indicates a I dB limit of above 100 km for optimum modulation index of 0.5. For this index, simulations indicate the existence of a maximum allowable input power around +I8 dBm, above which the channel breaks down. This also applies for dispersion shijied fiber, even at a lower power of around +14 dBm.