Alignment of Free-Space Coupling of Few-Mode Fibre to Multi-Mode Fibre using Digital Holography

Off-axis digital holography is used to align a few-mode fiber to a multi-mode fiber in a free-space optical setup. Alignment based on power coupling measurements alone cannot guarantee low mode-dependent loss. The proposed alignment method enables reliable fiber coupling with low mode-dependent loss and crosstalk

High pressure CVD inside microstructured optical fibres

We report the fabrication of semiconductor structures within holey fibres via a pressure driven microfluidic chemical vapour deposition process, demonstrating templated growth of crystalline Group IV semiconductor structures and devices in extreme aspect ratio geometries

Deposition of electronic and plasmonic materials inside microstructured optical fibres

Optical fibres are the transport medium of today's digital information. Nowadays, modern optical telecommunication systems make use of semiconductor optoelectronic devices to generate, control and detect light. The union of the two technologies, namely fibre photonics and semiconductor electronics is expected to have a major impact on next generation of optoelectronic devices, exploiting both the guiding capabilities of optical fibres and the signal processing properties of semiconductors devices. Only recently, with the advent of microstructured optical fibres and templating material processing methods, it has been possible to create optical fibres with solid-state material inclusions. An experimental investigation on the optical transmission properties of microstructured optical fibres impregnated with silver nanoparticles is also presented. These fibres are shown to be an excellent way of coupling optical guided modes into surface plasmons. As a result, they represent a promising platform technology for fully integrated photonic/plasmonic devices. These fibres have demonstrated the enhancement of Raman signals from molecules adsorbed onto the inner metal surfaces and thus ideally suited for Surface Enhance Raman Scattering molecular detection

Highly efficient surface enhanced Raman scattering using microstructured optical fibers with enhanced plasmonic interactions

Microstructured optical fibers "MOFs" represent a promising platform technology for fully integrated photonic-plasmonic devices. In this paper, we experimentally investigate the properties of two MOF templates impregnated with silver nanoparticles via a high pressure chemical deposition technique. By comparing fiber templates with different air filling fractions, we have quantified the importance of an increased field-particle overlap for improved surface enhanced Raman scattering sensitivity for the next generation of optical fiber sensors

Multimode And Coupled-Core Fiber Amplifiers For Sdm

We discuss two Er-doped fiber amplifier designs based on multimode and coupled-core structures. The fiber amplifiers not only reduce the mode dependent gain but also provide large output power at low noise figure

Single Carrier 1 Tbit/S Mode-Multiplexed Transmission Over Graded-Index 50Μm Core Multi-Mode Fiber Employing Kramers-Kronig Receivers

We experimentally demonstrate 1 Tbit/s net transmission over 12 spatial channels (6 modes, 2 polarizations) up to 18 km, and 500 Gbit/s net transmission over 6 spatial channels up to 53 km using Kramers-Kronig receivers

Mode-dependent Loss and Gain Estimation in SDM Transmission Based on MMSE Equalizers

The capacity of space division multiplexing (SDM) systems with coupled channels is fundamentally limited by mode-dependent loss (MDL) and mode-dependent gain (MDG) generated in components and amplifiers. In these systems, MDL/MDG must be accurately estimated for performance analysis and troubleshooting. Most recent demonstrations of SDM with coupled channels perform MDL/MDG estimation by digital signal processing (DSP) techniques based on the coefficients of multiple-input multiple-output (MIMO) adaptive equalizers. Although these methods provide a valid indication of the order of magnitude of the accumulated MDL/MDG over the link, MIMO equalizers are usually updated according to the minimum mean square error (MMSE) criterion, which is known to depend on the channel signal-to-noise ratio (SNR). Therefore, MDL/MDG estimation techniques based on the adaptive filter coefficients are also impaired by noise. In this paper, we model analytically the influence of the SNR on DSP-based MDL/MDG estimation, and show that the technique is prone to errors. Based on the transfer function of MIMO MMSE equalizers, and assuming a known SNR, we calculate a correction factor that improves the estimation process in moderate levels of MDL/MDG and SNR. The correction factor is validated by simulation of a 6-mode long-haul transmission link, and experimentally using a 3-mode transmission link. The results confirm the limitations of the standard estimation method in scenarios of high additive noise and MDL/MDG, and indicate the correction factor as a possible solution in practical SDM scenarios

Single carrier 1 Tbit/s mode-multiplexed transmission over graded-index 50μm core multi-mode fiber employing Kramers-Kronig receivers

We experimentally demonstrate 1 Tbit/s net transmission over 12 spatial channels (6 modes, 2 polarizations) up to 18 km, and 500 Gbit/s net transmission over 6 spatial channels up to 53 km using Kramers-Kronig receivers

1 Tbit/s/λ Transmission Over a 130 km Link Consisting of Graded-Index 50 μm Core Multi-Mode Fiber and 6LP Few-Mode Fiber

We demonstrate 1 Tbit/s/λ single-span transmission over a heterogeneous link consisting of graded-index 50 μm core multi-mode fiber and 6LP few-mode fiber using a Kramers-Kronig receiver structure. Furthermore, the link budget increase by transmitting only three modes while employing more than three receivers is investigated

Surface enhanced Raman scattering using metal modified microstructured optical fiber substrates

In this paper we report the fabrication of microstructured optical fibers (MOFs) metallic metamaterials using a bottom-up processing technique for surface enhanced Raman scattering (SERS) applications. The inner walls of the silica-based holey optical fiber have been modified by depositing granular films of Ag nanoparticles from its organometallic precursor at high pressure condition. The resulting fibers demonstrate strong SERS effect when analyte molecules are infiltrated within the MOF due to large electromagnetic field enhancement and long interaction length. The chemically modified MOFs with 3D patterning represent an exciting platform technology for next generation SERS sensors and plasmonic in-fiber integrated devices