Martin E. V. Pedersen

A silica based highly nonlinear fibre with improved threshold for stimulated brillouin scattering

8.8 dB improvement in figure of merit for SBS limited highly nonlinear fibres is reported by using a combination of Al-doping and straining of the fibre.

Time-domain multimode dispersion measurement in a higher-order-mode fiber

We present a new multimode dispersion measurement technique based on the time-of-flight method. The modal delay and group velocity dispersion of all excited modes in a few-mode fiber can be measured simultaneously by a tunable pulsed laser and a high speed sampling oscilloscope. A newly designed higher-order-mode fiber with large anomalous dispersion in the LP(02) mode has been characterized using this method, and experimental results are in good agreement with the designed dispersion values. The demonstrated technique is significantly simpler to implement than the existing frequency-domain or interferometry-based methods.

Silica-based highly nonlinear fibers with a high SBS threshold

Results on the suppression of stimulated Brillouin scattering in highly non linear fibers with both germanium- and aluminum-doped cores based on spooling the fiber with a linear strain gradient are compared and presented.

Higher-order-mode fiber optimized for energetic soliton propagation.

We describe the design optimization of a higher-order-mode (HOM) fiber for energetic soliton propagation at wavelengths below 1300 nm. A new HOM fiber is fabricated according to our design criteria. The HOM fiber is pumped at 1045 nm by an energetic femtosecond fiber laser. The soliton self-frequency shift process shifts the center wavelength of the soliton to 1085 nm. The soliton has a temporal duration of 216 fs and a pulse energy of 6.3 nJ. The demonstrated pulse energy is approximately six times higher than the previous record in a solid core fiber at wavelengths below 1300 nm.

Intermodal four-wave mixing in a higher-order-mode fiber.

We demonstrate intermodal four-wave mixing in an all-fiber system between the LP01 and LP02 mode of a higher-order-mode fiber. Anti-Stokes and Stokes light with 2 nJ pulse energy is generated with 20% conversion efficiency.

Intermodal Čerenkov radiation in a higher-order-mode fiber.

We demonstrate an intermodal Čerenkov radiation effect in a higher-order-mode (HOM) fiber with a mode crossing (i.e., two guided modes having the same propagation constant at the same wavelength). A frequency-shifted soliton in the vicinity of the mode-crossing wavelength emits a phase-matched dispersive wave in a different propagation mode. We develop a theoretical explanation for this nonlinear optical effect and demonstrate that the mode crossing in HOM fibers can be utilized to achieve simultaneous wavelength and mode conversion; the strength of this intermodal nonlinear interaction can be tuned by controlled fiber bending.

Polarization-maintaining higher-order mode fiber module with anomalous dispersion at 1 μm

This Letter demonstrates a polarization-maintaining higher-order mode fiber module that has anomalous dispersion at 1xa0μm. The group velocity dispersion of the module is measured, showing a split of the two polarization axes. The excellent polarization-maintaining properties of the relevant fiber modes for the higher-order mode fiber are likewise demonstrated employing a new simple method for the measurement of the beat length of higher-order modes at a single wavelength. The higher-order fiber module is intended for group velocity dispersion compensation.

Measurement of spatial and polarization birefringence in two-mode elliptical core fibers

By analyzing the SOP evolution as function of wavelength the group birefringence of both the polarization and spatial modes of elliptical-core two-mode fibers with systematically varied ellipticity (b/a≈0.1-0.64) is measured over a broad wavelength range around 1550 nm.

Slow-light enhanced optical detection in liquid-infiltrated photonic crystals

Slow-light enhanced optical detection in liquid-infiltrated photonic crystals is theoretically studied. Using a scattering-matrix approach and the Wigner–Smith delay time concept, we show that optical absorbance benefits both from slow-light phenomena as well as a high filling factor of the energy residing in the liquid. Utilizing strongly dispersive photonic crystal structures, we numerically demonstrate how liquid-infiltrated photonic crystals facilitate enhanced light–matter interactions, by potentially up to an order of magnitude. The proposed concept provides strong opportunities for improving existing miniaturized absorbance cells for optical detection in lab-on-a-chip systems.

Transverse Field Dispersion in the Generalized Nonlinear Schrödinger Equation: Four Wave Mixing in a Higher Order Mode Fiber

An improved version of the generalized nonlinear Schrödinger equation is derived, which takes into account the correct dispersion of the transverse field distribution. The new improved version of the generalized nonlinear Schrödinger equation is verified to give the same results as the standard implementation for a simple single mode soliton propagation example. As opposed to the standard implementation, the new implementation is able to reproduce pulsed four wave mixing observed experimentally in a higher order mode fiber.