Electrically tunable Yb-doped fiber laser based on a liquid crystal photonic bandgap fiber device.

We demonstrate electrical tunability of a fiber laser using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a tunable liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate an all-spliced laser cavity based on the liquid crystal photonic bandgap fiber mounted on a silicon assembly, a pump/signal combiner with single-mode signal feed-through and an ytterbium-doped photonic crystal fiber. The laser cavity produces a single-mode output and is tuned in the range 1040-1065 nm by applying an electric field to the silicon assembly.

Liquid crystal parameter analysis for tunable photonic bandgap fiber devices.

We investigate the tunability of splay-aligned liquid crystals for the use in solid core photonic crystal fibers. Finite element simulations are used to obtain the alignment of the liquid crystals subject to an external electric field. By means of the liquid crystal director field the optical permittivity is calculated and used in finite element mode simulations. The suitability of liquid crystal photonic bandgap fiber devices for filters, waveplates or sensors is highly dependent on the tunability of the transmission spectrum. In this contribution we investigate how the bandgap tenability is determined by the parameters of the liquid crystals. This enables us to identify suitable liquid crystals for tunable photonic bandgap fiber devices.

On-chip tunable long-period grating devices based on liquid crystal photonic bandgap fibers.

We design and fabricate an on-chip tunable long-period grating device by integrating a liquid crystal photonic bandgap fiber on silicon structures. The transmission axis of the device can be electrically rotated in steps of 45 degrees as well as switched on and off with the response time in the millisecond range. The strength of the loss peak is controlled electrically, and the spectral position of the loss peak is thermally tunable. This compact design results in a stable grating and permits this device to be more easily applied in practical systems.

Biased liquid crystal infiltrated photonic bandgap fiber.

A simulation scheme for the transmission spectrum of a photonic crystal fiber infiltrated with a nematic liquid crystal and subject to an external bias is presented. The alignment of the biased liquid crystal is simulated using the finite element method to solve the relevant system of coupled partial differential equations. From the liquid crystal alignment the full tensorial dielectric permittivity in the capillaries is derived. The transmission spectrum for the photonic crystal fiber is obtained by solving the generalized eigenvalue problem deriving from Maxwell's equations using a vector element based finite element method. We demonstrate results for a splay aligned liquid crystal infiltrated into the capillaries of a four-ring photonic crystal fiber and compare them to corresponding experiments.

Continuously tunable all-in-fiber devices based on thermal and electrical control of negative dielectric anisotropy liquid crystal photonic bandgap fibers.

We infiltrate photonic crystal fibers with a negative dielectric anisotropy liquid crystal. A 396 nm bandgap shift is obtained in the temperature range of 22-80 degrees C, and a 67 nm shift of long-wavelength bandgap edge is achieved by applying a voltage of 200 Vrms. The polarization sensitivity and corresponding activation loss are measured using polarized light and a full broadband polarization control setup. The electrically induced phase shift on the Poincaré sphere and corresponding birefringence change are also measured. According to the results, tunable wave plates working in the wavelength range of 1520-1580 nm and a potential for realizing a polarimeter working at the 1310 nm region are experimentally demonstrated.