We present the design of a photonic crystal fiber which promises to yield very large optical nonlinearity ∼151 W−1 km−1 at 1.55 μm wavelength. The fiber possesses two zero dispersion points whose locations can be tuned by varying the air hole diameter and hole pitch. The fiber dispersion is anomalous between these two zero dispersion points and its value is moderate. The fiber has been used to numerically simulate optical supercontinuum (SC) generation using low power pump pulses of 50 fs duration at a 1.55-μm wavelength. At the end of 15-cm fiber, SC broadening of about 1200 and 1700 nm can be achieved with pulses of 1 and 5 kW peak power, respectively.
Slow light propagated through a photonic crystal with a nematic liquid crystal-filled cavity has been simulated and presented. Both slow and fast modes propagate in the waveguide. Design efforts were made to adjust the group velocities of the propagating modes. Numerical studies show that the nematic liquid crystal provides designers an additional degree of freedom to tune the device by using external perturbations such as applying heat or electric field. Comparative studies have also been done to see the performance of the devices built in two different material platforms (silicon and InP). The device can be used as an economic and efficient functional materials system for building robust integrated photonic devices that have the ability to slow, store, and process light pulses.
An innovative technique to tune the slow light propagated through photonic crystal cavity filled with E7 type
nematic crystal has been simulated and presented. Observed propagating modes in the previously fabricated photonic
crystal indicate that both slow and fast modes propagate in the waveguide. Design efforts were made to adjust the
propagating modes as well as their group velocities. Numerical studies show that by inserting nematic liquid crystal,
designer can achieve additional degree of freedom to tune the device by using external perturbation such as applying heat
or electric field. Comparative studies have also been done to see the performance of the devices fabricated in two
deferent material platforms (silicon and InP) with an objective to develop economic and efficient functional material
systems for building robust integrated photonic devices that have the ability to slow, store, and process light pulses.
An experimental characterization of broadband semiconductor optical amplifiers (SOAs) at 1360 nm is reported. In addition to their inherent small size, fast dynamics, and feasibility of integration with other optoelectronic components, the relevance of the multi quantum well (MQW) asymmetric SOAs here reported relies on the achievement of a flat and broad 3 dB amplification bandwidth. SOAs are composed of nine In1-xGaxAsyP1-y 0.2% tensile strained MQW layers separated by latticed matched InP barriers. The asymmetry of the active region is based on the difference of the molar concentrations, with Ga (x) ranging from 0.46 to 0.47 and As (y) ranging from 0.89 to 0.94. Devices under test have 7 degrees tilt cleaved facets and feature different geometries: ridge widths from 2 to 4 μm in steps of 0.25 μm, and cavity lengths of 600, 900, 1200, and 1500 μm. Fabry-Pérot (FP) lasers with the same material composition as the SOAs and within the same wafer are used as test structures for parameters extraction, providing a feedback mechanism for further design improvement. The ridge width of the FP lasers varies from 2 to 8 μm, in steps of 2 μm. All the devices have been designed and characterized at the Photonics Technology Laboratory, Centre for Research in Photonics, fabrication was done at Canadian Photonics Fabrication Centre (CPFC), Canada and supported by CMC Microsystems.
Devices under test are DC-biased and temperature controlled at 25°C. A single pass gain of 13.5 dB is measured for a 3 dB bandwidth of 60 nm centred at 1360 nm. Light-current plots obtained from the FP lasers show that the threshold current varies with the cavity length, with a minimum of 80 mA for a cavity length of 600 μm and a ridge width of 2 μm. A thermal roll-off occurring at high injection currents is observed, especially with the smallest cavity length. In conclusion, asymmetric MQW SOAs featuring different ridge widths and cavity lengths have been
The structuring of high quality complex optical materials yields remarkable flexibility in the fabrication of
nanostructures. These artificial materials can be used to manipulate light. The photonic band structure of a honey comb
lattice composed of hollow shell rod with GaAs wall has been investigated by using standard Eigen mode expansion
(EME) techniques. The dispersion characteristics of the dielectric material determine the tunability of the band gap as
well as appearance of surface plasmon polariton (SPP) mode. Dispersion less flat band was observed for the frequency
region where dielectric constant changes its sign. We demonstrate band gap tuning by applying external perturbation
such as temperature change or varying external magnetic field. Using our band solver we extend the existing
methodology by adjusting the dimension of the lattice to observe the desired effects. In addition to that our method
studies the lacking of structural integrity due to presence of absorption.
In this paper, we proposed a bidirectional coupler implemented in a dual-core photonic crystal fiber (PCF) that has
nematic liquid crystal filled holes in the cladding region. Light wave is guided in this PCF by total internal reflection
(TIR) due to the refractive index contrast between soft glass and liquid crystal. Its coupling, birefringence and dispersion
characteristics are evaluated. The coupler can be used to realize wavelength selective MUX-DEMUX as well as a
polarization compensator for wavelength division multiplexing (WDM) application. Moreover the device demonstrates
tunability with temperature change.
The performance of two different photonic crystal fibers (PCF) of identical lengths for implementation of the Stokes
source in a multimodal CARS microscopy and spectroscopy setup is compared. RIN measurements are performed to
experimentally determine the noise in the supercontinuum from the two fibers as well as in the CARS signal under
similar excitation conditions of the input pulse into the PCF. The RIN of the CARS signal is found to be higher than
the RIN of the corresponding Stokes signal, in both fibers. The implications for CARS microscopy of the SC spectrum
and its noise dependence on input pulse conditions in both fibers, are discussed.