M.A.F. Roelens

Low-threshold supercontinuum generation in highly nonlinear chalcogenide nanowires

We demonstrate low-threshold supercontinuum generated in a highly nonlinear arsenic selenide chalcogenide nanowire with tailored dispersion. The tapered submicrometer chalcogenide fiber exhibits an ultrahigh nonlinearity, n(2) approximately 1.1x10(-17) m(2)/W and an effective mode area of 0.48 mum(2), yielding an effective nonlinearity of gamma approximately 93.4 W/m, which is over 80,000 times larger than standard silica single-mode fiber at a wavelength of approximately 1550 nm. This high nonlinearity, in conjunction with the engineered anomalous dispersion, enables low-threshold soliton fission leading to large spectral broadening at a dramatically reduced peak power of several watts, corresponding to picojoule energy.

Dispersion Trimming in a Reconfigurable Wavelength Selective Switch

We experimentally demonstrate dispersion compensation in a wavelength selective switch, and characterize the bandwidth-dispersion product. At a channel bit-rate of 80 Gbit/s, we compensate for various amounts of dispersion (up to ±60 ps/nm), tunable for each wavelength division multiplexed channel, solely by adjusting the phase front of the optical signal inside the wavelength selective switch. Error-free operation is obtained for all of the channels, and for each output port after propagation over various lengths of dispersive fiber.

Ultra-flat SPM-broadened spectra in a highly nonlinear fiber using parabolic pulses formed in a fiber Bragg grating

We propose a new method for generating flat self-phase modulation (SPM)-broadened spectra based on seeding a highly nonlinear fiber (HNLF) with chirp-free parabolic pulses generated using linear pulse shaping in a superstructured fiber Bragg grating (SSFBG). We show that the use of grating reshaped parabolic pulses allows substantially better performance in terms of the extent of SPM-based spectral broadening and flatness relative to conventional hyperbolic secant (sech) pulses. We demonstrate both numerically and experimentally the generation of SPM-broadened pulses centred at 1542 nm with 92% of the pulse energy remaining within the 29 nm 3 dB spectral bandwidth. Applications in spectra slicing and pulse compression are demonstrated.

Spectral modeling of channel band shapes in wavelength selective switches

A model for characterizing the spectral response of the passband of Wavelength Selective Switches (WSS) is presented. We demonstrate that, in contrast to the commonly used supergaussian model, the presented model offers a more complete match to measured results, as it is based on the physical operation of the optical system. We also demonstrate that this model is better suited for calculation of WSS channel bandwidths, as well as predicting the final bandwidth of cascaded WSS modules. Finally, we show the utility of this model in predicting channel shapes in flexible bandwidth WSS channel plans.

Advances in high power short pulse fiber laser systems and technology

We review recent advances in Yb fiber lasers and amplifiers for high power short pulse systems. We go on to describe associated recent developments in fiber components for use in such systems. Examples include microstructured optical fibers for pulse compression and supercontinuum generation, and advanced fiber grating technology for chirped-pulse amplifier systems.

1x11 few-mode fiber wavelength selective switch using photonic lanterns

We demonstrate an 11 port count wavelength selective switch supporting spatial superchannels of three spatial modes, based on the combination of photonic lanterns and a high-port count single-mode WSS.

Reconfigurable Optical Pulse Generator Employing a Fourier-Domain Programmable Optical Processor

This paper demonstrates a reconfigurable optical pulse generator based on the creation of a high-quality flat continuum that covers the C-band, followed by the tailoring of the spectral amplitude and phase of the continuum using a commercially available reconfigurable programmable optical processor in order to provide an arbitrary picosecond pulse shape or width. The highly efficient continuum is achieved by seeding a highly nonlinear fiber with transform-limited 4 ps parabolic-shaped pulses. A 20 nm 3 dB continuum at the very high repetition rate of 40 GHz is generated. Fourier-domain pulse shaping techniques are then applied to this continuum via the programmable optical processor to generate any arbitrary pulse shape. We present two specific pulse shaping examples suitable for a variety of high-bit-rate applications. The first example shows the improvement in pulse quality using tailored compression techniques over conventional methods and the second example presents multiwavelength pulse generation, which demonstrates the flexibility and range of pulse shapes that can be achieved using this system. Experimental findings are supported with theoretical results.

An optical FPGA: reconfigurable simultaneous multi-output spectral pulse-shaping for linear optical processing

We demonstrate a pulse-shaping technique that allows for spectrally resolved splitting of an input signal to multiple output ports. This ability enables reconfigurable creation of splitters with complex wavelength-dependent splitting ratios, giving similar flexibility to a Field Programmable Gate Array (FPGA) in electronics. Our technique can be used to create reprogrammable optical (interferometric) circuits, by emulating their multi-port spectral transfer functions instead of the traditional method of creating an interferometer by splitting and recombining the light with an added delay. We demonstrate the capabilities of this technique by creating a Mach-Zehnder interferometer, an all-optical discrete Fourier transform filter, two nested Mach-Zehnder interferometers and a complex splitter with a triangular-shaped response.

Multi-wavelength synchronous pulse burst generation with a wavelength selective switch

We demonstrate simultaneous pulse-shaping at different ports of a rapidly tunable wavelength selective switch at a base rate of 40 GHz, based on Fourier-domain pulse shaping. Various pulse bursts are generated and accurately characterized with a linear spectrographic method.

Comparison between nonlinear and linear spectrographic techniques for the complete characterization of high bit-rate pulses used in optical communications

Two spectrographic techniques for the complete characterization (amplitude and phase) of optical pulses with durations commensurate with high bit-rate communications systems (2-30 ps) are experimentally compared. We show that a highly sensitive linear sampling technique utilizing an electroabsorption modulator gives accurate results when compared to a nonlinear sampling technique based on second-harmonic generation over a range of pulse durations from 2-33 ps.