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.
In this paper we introduce a multi gas sensor system based on refractive index changes in a 2D slab photonic crystal. The
sensor is formed by a L3 resonant cavity sandwiched between two W1.06 waveguides in the photonic crystal. The sensor
configuration is similar to an Add-Drop filter structure. The transmission spectrums of the sensor with different ambient
refractive indices ranging from n = 1.0 to n = 1.1 are calculated. The simulation results show that a change in ambient RI
of Δn = 0.0008 is apparent with a corresponding change in output wavelength of the sensor of 2.4 nm. The properties of
the sensor are simulated using the 3D finite-difference time-domain (FDTD) method. The Q-factor of the sensor is also
optimized, with highest values reaching over 30,000. The sensor system is hybrid integrated with a wireless RF chip
which processes the sensor data and transmits them in effect turning the entire system into a wireless sensor mote.
Stability and linewidth (FWHM & 20-dB) measurements of a tuneable, high power, narrow linewidth multiwavelength Hybrid Cavity Semiconductor Fibre Ring Laser (HC-SFRL) are presented. The laser incorporates a SOA, a polarization controller (PC), and a tuneable optical filter. The ring cavity itself is composed of Single Mode Fibre (SMF) and a 1-m long Polarization Maintaining Fibre (PMF). The laser is capable of single, dual and triple lasing wavelengths with ultra-narrow wavelength spacing (less than 30 pm) with good stability for periods over 2 hours.
A novel SOA based fibre ring laser is presented. An S-band optimized SOA is added to the cavity of a C-band SOA fibre
ring laser resulting in significant improvements in the ring laser characteristics. Three main linewidth control parameters
are identified: 1) Bias current of C-band SOA, 2) Bias current of S-band SOA, and 3) SOP of lasing light in ring's
cavity. Experimental measurements suggest the SOP of the lasing light to be the dominant control parameter for
reduction or enhancement of the laser's linewidth. An output power level of 5.27 dBm (corresponding to 10.54 dBm
cavity power) and less than 20 kHz FWHM (limited by equipment resolution) and 190 kHz 20-dB linewidth at 1558 nm
is demonstrated. The measured 20-dB linewidths displayed stronger variations to changes in the bias currents of the ring
lasers compared to variations in the FWHM. This suggests that the optical spectrum of the ring lasers becomes
asymmetric at high bias currents and is no longer pure Lorentzian.