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We demonstrate a harmonically mode-locked dispersion-managed polarization-maintaining erbium fiber laser that uses photonic crystal fiber for nonlinear pulse compression. The high nonlinearity and large anomalous dispersion of the PCF resulted in significant reduction in the cavity length and increased the long-term stability. The laser cavity, only 36-m-long, yielded stable 1.3 ps pulses at a 40-GHz repetition-rate, with supermode noise suppression of over 60 dB.

We demonstrate the adiabatic soliton compression of a dual frequency beat signal using distributed Raman amplification (DM) in a dispersion decreasing fiber (DDF). A 40 GHz beat signal generated from a LiNbO modulator at a driving RF frequency of 20 GHz is compressed into ∼ 2.2 ps soliton pulses using DRA in a 20 km DDF. The generation of high quality of soliton pulses from the 40 GHz sinusoidal beat signal is readily achieved with a significantly enhanced compression efficiency using DDF based DRA, compared to the case of using a DDF without DRA or a DSF with DRA.

We propose a novel all-optical signal processor for use at a return-to-zero receiver utilising loop mirror intensity filtering and nonlinear pulse broadening in normal dispersion fibre. The device offers reamplification and cleaning up of the optical signals, and phase margin improvement. The efficiency of the technique is demonstrated by application to 40 Gbit/s data transmission.

We present the modification of decoder for 2-D Wavelength/Time (W/T) Optical Code Division Multiple Access (O-CDMA) system by optical hard-limiters. The performance improvement of the system using proposed decoder modification is shown by numerical simulation of the average Signal to interference difference and Bit error probability as a function of active user number and weight of codeword for the different topology of the decoder. The influence of non-ideal properties of the used optical hard-limiters upon the bit error probability in system is studied.

Integration of the all-optical analog-to-digital (A/D) converter using self-frequency shifting in fiber and a pulse-shaping technique is described. Optical A/D conversion has attracted much attention, in order to realize high-speed and high-throughput system for photonic networks. A/D conversion generally consists of sampling, quantization and coding. Whereas various optical sampling techniques have been proposed, there are few investigations of the optical quantization and optical coding. Previously, we have proposed an all-optical A/D converter. In this paper, we aim at the integration of the proposed all-optical A/D converter using high nonlinear fiber, arrayed waveguide grating, and variable optical attenuator, and demonstrate its operation.

BER improvement of 15 decades is observed using an asymmetric NOLM at a bitrate of 40Gbit/s and an input OSNR of 28.7dB. The BER improvement can be converted into 3.9dB of OSNR gain. Both were achieved by optimizing NOLM input power and splitting ratio. This allows for longer spans and thus reduces the over all amount of amplifiers or allows for an increased system reach.

Use the method we developed recently we calculate the bit-error-rate (BER) improvement as a function of transmitter extinction ratio and the optical link noise parameter.

Apodized waveguide Bragg gratings are written using Sagnac type interferometer. As the quality of these gratings is not enough for DWDM devices, a procedure for shaping of filter profiles was developed. Obtained 10 mm long grating gives line width of 0.4 nm and almost completely suppressed side lobes.

We propose and demonstrate an external optical modulation method based on TE/TM-mode absorption nulls in a Multiple Quantum Well (MQW) Fabry-Perot laser diode (FP-LD). The center wavelength of the absorption nulls is rapidly shifted to short-wavelength by the small current change (∼ 1mA) in the FP-LD, which can modulate optical signal with more than 10 dB of extinction ratio (ER). The shift of the center wavelength comes from the refractive index change due to anomalous dispersion and plasma effect in MQW FP-LD waveguide. Non-inverting and inverting signals are made by TE- and TM-mode absorption nulls at 155.52 Mbps and BERs for the signals are measured, respectively.

We present a field model of a full Encoder/Decoder (E/D) in a Waveguide Grating Router (WGR) configuration that generates/processes a set of Phase- Shift Keyed (PSK) codes. We furnish the design procedure to synthesize the device, determining the optimal number of the ports and the tolerance in the differential path length as functions of the code detection parameter.