Jesús Liñares

Mode-division multiplexed transmission with inline few-mode fiber amplifier

We demonstrate mode-division multiplexed WDM transmission over 50-km of few-mode fiber using the fibers LP01 and two degenerate LP11 modes. A few-mode EDFA is used to boost the power of the output signal before a few-mode coherent receiver. A 6×6 time-domain MIMO equalizer is used to recover the transmitted data. We also experimentally characterize the 50-km few-mode fiber and the few-mode EDFA.

1.05Pb/s Transmission with 109b/s/Hz Spectral Efficiency using Hybrid Single- and Few-Mode Cores

We demonstrated 1.05-Pb/s transmission over 3km of multicore fiber with spectral efficiency of 109b/s/Hz, using twelve single-mode cores carrying DP-32QAM-OFDM signals and two few-mode cores carrying DP-QPSK in their LP01 and two LP11 modes.

Hole-Assisted Few-Mode Multicore Fiber for High-Density Space-Division Multiplexing

A seven-core few-mode multicore fiber in which each core supports both the LP01 mode and the two degenerate LP11 modes has been designed and fabricated for the first time, to the best of our knowledge. The hole-assisted structure enables low inter-core crosstalk and high mode density at the same time. LP01 inter-core crosstalk has been measured to be lower than -60 dB/km. LP11 inter-core crosstalk has been measured to be around -40 dB/km using a different setup. The LP11 free-space excitation-induced crosstalk is simulated and analyzed. This fiber allows multiplexed transmission of 21 spatial modes per polarization per wavelength. Data transmission in LP01/LP11 mode over 1 km of this fiber has been demonstrated with negligible penalty.

SDM transmission of real-time 10GbE traffic using commercial SFP + transceivers over 0.5km elliptical-core few-mode fiber

We experimentally demonstrate the first few-mode space division multiplexed (SDM) transmission of real-time 10Gb/s Ethernet (10GbE) traffic using commercial small form-factor pluggable SFP + transceivers without coherent detection or multiple input multiple output digital signal processing (MIMO-DSP) over 0.5km elliptical-core few-mode-fiber, achieving <-26dB crosstalk between LP(11e) and LP(11o) modes at 1.3μm.

Optical path integrals in gradient-index media

A path integral has been used to evaluate, in paraxial approximation, the complex amplitude transmitted through gradient-index media. This formulation is useful for examining propagation in gradient-index media.

New glasses for graded-index optics: influence of non-linear diffusion in the formation of optical microstructures

Abstract We have designed novel glasses for the formation of graded-index diffractive optical structures. In these glasses silver ion exchange and rapid diffusion produce a large refractive-index variation (0.085). We model the non-linearity of the diffusion process by applying the Boltzmann–Matano technique to the optical profiles and use index variation rather than concentration in the second Fick equation. The simulation of graded-index diffraction gratings formed under thermal and electrically assisted diffusion shows that, other conditions being equal, more efficient gratings can be formed when the diffusion coefficient increases with the dopant concentration. According to the simulation, the application of an electric field of about 0.5 V/μm enables one to obtain a phase shift equal to 1.5 π rad if a grating with a period of 4 μm is formed in the novel glass material. For comparison, a phase shift of only 0.9 π is predicted when a similar grating is formed in the commercial BK-7 glass.

Arbitrary single-mode coupling by tapered and nontapered grin fiber lenses.

Arbitrary modal field coupling is analyzed and optimized by using tapered and nontapered GRIN fiber lenses as single-mode optical fiber connectors. Conditions for achieving maximum coupling efficiency are derived.

Paraxial Fourier transforming and imaging properties of a GRIN lens with revolution symmetry: GRIN lens law

Wave description and ray matrix methods have been used to study the paraxial Fourier transforming and imaging properties of GRIN lenses with revolution symmetry. Using these properties, the GRIN lens law and the Fourier transforming condition are derived for a simple optical system.

Modal coupling analysis for integrated optical components in glass and lithium niobate.

Coupling efficiency between the fundamental modes of two different graded-index waveguides, which are fabricated in glass or lithium niobate, is calculated by numerical and variational methods. Analytical results are derived by the variational approach, which supplies a systematic method for studying the influence of modal coupling on the design of integrated optical components.

A novel refractive index profile for optical characterization of nonlinear diffusion processes and planar waveguides in glass

Abstract A novel refractive index profile, consistent with nonlinear diffusion processes in glass, is proposed for graded index (GRIN) planar waveguides. This new profile matches with great accuracy most of the waveguides fabricated by ion-exchange in glass, and it provides simple relationships between the real diffusion parameters and the effective ones obtained by fitting to the experimental results. In this way, physical parameters such as the diffusion coefficients can be easily determined and the numerical solution, describing the ion-exchange process, can be directly selected.