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We propose the amplification of 12 OAM modes in an air-core EDF using either core- or cladding- pumping at 980nm. Differential modal gains of only 0.25dB among all the 12-modes are achieved over the C-band.

We theoretically and experimentally study third harmonic generation in silica microfibres. Phase matching at critical diameters was achieved by intermodal-coupling with higher order third harmonic modes, which were successfully generated using 4ns 1.55µm pump pulses.

We demonstrate selective transmission and absorption of 1-ps pulses, pulse shaping and 1-ps dark pulse generation in a fiber-optic device based on a plasmonic metamaterial, providing an example of all-optical signal processing with THz bandwidth.

We report what we believe to be the first experimental study of inter-modal cross-gain modulation and associated transient effects as different spatial modes and wavelength channels are added and dropped within a two-mode amplifier for SDM transmission.

We review the performances of both core and cladding pumped few-mode erbium doped fiber amplifiers supporting 6 spatial modes (4 mode groups) which incidentally the highest mode count demonstrated to date Refereed/Peer-reviewed

We report broadband long-period gratings on a hollow optical fiber corrugated by a femotosecond laser. The center wavelength and the coupling strength of the peak could be controlled by changing the width of the corrugation.

We report for the first time coherently-detected, polarization-multiplexed transmission over a photonic band gap fiber. By transmitting 96 x 320-Gb/s DP-32QAM modulated channels, a net data rate of 24 Tb/s was obtained.

Microwires and nanowires have been manufactured by using a wide range of bottom-up techniques such as chemical or physical vapor deposition and top-down processes such as fiber drawing. Among these techniques, the manufacture of wires from optical fibers provides the longest, most uniform and robust nanowires. Critically, the small surface roughness and the high-homogeneity associated with optical fiber nanowires (OFNs) provide low optical loss and allow the use of nanowires for a wide range of new applications for communications, sensing, lasers, biology, and chemistry. OFNs offer a number of outstanding optical and mechanical properties, including (1) large evanescent fields, (2) high-nonlinearity, (3) strong confinement, and (4) low-loss interconnection to other optical fibers and fiberized components. OFNs are fabricated by adiabatically stretching optical fibers and thus preserve the original optical fiber dimensions at their input and output, allowing ready splicing to standard fibers. A review of the manufacture of OFNs is presented, with a particular emphasis on their applications. Three different groups of applications have been envisaged: (1) devices based on the strong confinement or nonlinearity, (2) applications exploiting the large evanescent field, and (3) devices involving the taper transition regions. The first group includes supercontinuum generators, a range of nonlinear optical devices, and optical trapping. The second group comprises knot, loop, and coil resonators and their applications, sensing and particle propulsion by optical pressure. Finally, mode filtering and mode conversion represent applications based on the taper transition regions. Among these groups of applications, devices exploiting the OFN-based resonators are possibly the most interesting; because of the large evanescent field, when OFNs are coiled onto themselves the mode propagating in the wire interferes with itself to give a resonator. In contrast with the majority of high-Q resonators manufactured by other means, the OFN microresonator does not have major issues with input-output coupling and presents a completely integrated fiberized solution. OFNs can be used to manufacture loop and coil resonators with Q factors that, although still far from the predicted value of 10. The input-output pigtails play a major role in shaping the resonator response and can be used to maximize the Q factor over a wide range of coupling parameters. Finally, temporal stability and robustness issues are discussed, and a solution to optical degradation issues is presented.

We experimentally demonstrate a means to selectively enhance wavelength conversion of WDM channels on a 100 GHz grid exploiting nonlinear effects between the spatial modes of a few mode fiber.

We propose and demonstrate the first low-latency 2-μm-band coherent NWDM transmission by on-chip spectral translation of 4×32-Gbaud 16-QAM signals with 33-GHz spacing. 318.25 Gbit/s net-rate is achieved with error-free performance after 1.15-km hollow-core fiber transmission.

We report broadband third harmonic generation via intermodal phase matching in silica microfibres of several centimetres. A 5 dB conversion bandwidth exceeding 36 nm was recorded, with harmonic power detected over a 150 nm range.

We provide the first demonstration of a high-bandwidth, low-intensity fiberized all-optical gate exploiting coherent absorption in a plasmonic metamaterial film. The fully packaged fiberized version of the switch has been tested to the bandwidth of 1 GHz while free-space versions of the gate have been shown to provide 100 THz bandwidth and to operate at arbitrarily low intensities. Our work illustrates how major bandwidth and energy challenges of optical telecommunications and information processing networks can be tackled by merging metamaterials and optical fibre technologies.

We experimentally demonstrate the selective amplification of structured light beams with >10W of output power for ~150 picosecond pulses in a few-mode Yb-doped large mode area fiber based Master Oscillator Power Amplifier (MOPA).

We show transmission of a 3x112-Gb/s DP-QPSK mode-division-multiplexed signal up to 80km, with and without multi-mode EDFA, using blind 6x6 MIMO digital signal processing. We show that the OSNR-penalty induced by mode-mixing in the multi-mode EDFA is negligible.

We demonstrate the generation and self-heterodyne detection of a 2-pm-band 32-Gbit/s line-rate 16-QAM signal based on inter-band wavelength conversion in an AlGaAsOI nanowaveguide. Error-free performance is achieved using LDPC codes with 33% overhead.

We present a fully integrated 32-core multicore fibre isolator with low insertion loss (average loss

We report the use of an optical microwire (OMW) with specifically designed transition region as an efficient tool to filter higher-order modes in multimode waveguides. Higher-order modes are effectively suppressed by controlling the transition taper profile and the diameter of the optical microwire. As a practical example, single-mode operation of a standard telecom optical fiber over a broad spectral window (400 ~ 1700 nm) was demonstrated with a 1 mum OMW.

A complete, realistic integrated system is investigated, consisting of directly spliced 7-core MCF, cladding-pumped 7-core amplifiers, isolators, and couplers. The system is demonstrated in a 16QAM C-band WDM scenario over 720 km.

We present recent advances in high spatial density multicore fiber amplifiers. The potential operational benefits are presented in comparison to standard erbium-doped fiber amplifiers and the potential cost/power saving benefits discussed.

We theoretically demonstrate the performance of a step index multimode (two mode-group) erbium-doped fiber amplifier with a localized erbium doped ring distribution for Space Division Multiplexed (SDM) transmission Refereed/Peer-reviewed

We experimentally demonstrate 10-Gbit/s OOK MIMO-less SDM transmission over 1 km of a three-spatial-mode elliptical-core fiber at 1550 nm. Negligible power penalty is achieved thanks to the low modal crosstalk (

We propose the cladding pumped four-mode-group and six-mode-group EDFA designs for mode division multiplexing transmission systems that provide less than 1 dB Differential Modal Gain (DMG) across the wavelength range of 1530-1600nm. © OSA 2014. Refereed/Peer-reviewed

We present an overview of recent progress on SDM components. In particular, we will discuss in detail various recently developed SDM fiber isolators, pump couplers and mode field diameter adaptors.

We demonstrate simultaneous modal gains of ~20dB for different pair-wise combinations of spatial and polarization modes in a MM-EDFA. The differential modal gains are reduced by fiber design and control of the pump field distribution.

Using micro-optic collimator technology, we present compact, low-loss optical interconnection devices for hollow core fibers (HCFs). This approach is one of the key manufacturing platforms for commercially available fiber optic components and most forms of HCFs can readily be incorporated into this platform without the need for any substantial or complicated adaptation or physical deformation of the fiber structure. Furthermore, this technique can provide for very low Fresnel reflection interconnection between solid-core fiber and HCF and in addition provides a hermetic seal for HCFs, which can be a critical issue for many HCF applications. In this paper, several exemplar HCF components are fabricated with low insertion loss (0.5-2 dB), low Fresnel reflection (−45 dB) and high modal purity (>20 dB) using various state-of-the-art HCFs.

We report the fabrication of a dual cladding large mode area thulium-doped germanate fiber (TDGF). The fiber has a core diameter of 20 µm, a high T m 3 + ion concentration of 3 c m 3 × 10 20 / c m 3 , and a hexagonal inner cladding to enhance pump absorption when cladding-pumped. Using a short fiber length, we demonstrate a compact 300 fs chirped-pulse amplification system operating at 1925 nm, investigating both core- and cladding-pumped implementations. By cladding pumping a 65 cm long fiber we produced an average power of 14.1 W (limited by thermally induced damage) and a peak power of 2.17 MW at a pulse repetition rate of 15.7 MHz. Core pumping a 19 cm length of TDGF produced 2.3 W of average-power and 16 MW peak-power pulses at 0.39 MHz. The performance is already comparable to the state-of-the-art success achieved with flexible silica fibers. Considering the rapid improvements in glass quality and the scope for further increasing the doping concentration, this fiber type holds great potential for pulsed fiber lasers in the 1.5–3 µm wavelength region.