Derryck T. Reid

Optical waveguide fabrication in z-cut lithium niobate (LiNbO3) using femtosecond pulses in the low repetition rate regime

Waveguide structures are fabricated in z-cut lithium niobate (LiNbO3) using focussed femtosecond pulses. Two different types of waveguide structure are fabricated depending on the pulse energy used. In the first, guiding occurs in regions directly surrounding a visible laser-damage region. In the second, guiding occurs in a material modification region created at the focus. High confinement guiding at 1550nm is demonstrated in the first type of waveguide but found to be temporary, thus indicating that at least part of the refractive index change is due to phenomena such as stress that are subject to relaxation. Finally, the polarization dependent guiding properties of the structures are investigated.

Femtosecond soliton pulse delivery at 800nm wavelength in hollow-core photonic bandgap fibers.

We describe delivery of femtosecond solitons at 800nm wavelength over five meters of hollow-core photonic bandgap fiber. The output pulses had a length of less than 300fs and an output pulse energy of around 65nJ, and were almost bandwidth limited. Numerical modeling shows that the nonlinear phase shift is determined by both the nonlinearity of air and by the overlap of the guided mode with the glass.

Ultrafast-laser inscription of a three dimensional fan-out device for multicore fiber coupling applications

A three dimensional fan-out device has been fabricated using ultrafast laser inscription. The device allows each core of a multicore fibre to be addressed individually by a single mode fiber held in an FVA.

Commercial Semiconductor Devices for Two Photon Absorption Autocorrelation of Ultrashort Light Pulses

Optical autocorrelation of ultrashort pulses using two photon absorption (TPA) in commercial semiconductor devices provides a convenient, sensitive, and inexpensive alternative to standard techniques using nonlinear crystals. A summary of readily available commercial devices suitable for TPA autocorrelation of picosecond and femtosecond pulses in the near-IR from 0.7–3 μm is presented.

Composite frequency comb spanning 0.4-2.4 μm from a phase-controlled femtosecond Ti: sapphire laser and synchronously pumped optical parametric oscillator

A repetition-rate-stabilized frequency comb ranging from the violet to the mid-infrared (0.4-2.4 microm) is obtained by phase locking a femtosecond Ti:sapphire laser and a synchronously pumped optical parametric oscillator to a common supercontinuum reference. The locking results have bandwidths lower than 3 kHz. By changing the locking frequencies, different relative and absolute offsets of the constituent frequency combs are achievable.

Mid-infrared dual-comb spectroscopy with an optical parametric oscillator

We present the first implementation of mid-infrared dual-comb spectroscopy with an optical parametric oscillator. Methane absorption spectroscopy was demonstrated with a resolution of 0.2 cm(-1) (5 GHz) at an acquisition time of ~10.4 ms over a spectral coverage at 2900-3050 cm(-1). The average power from each individual mid-infrared comb line was ~1 μW, representing a power level much greater than typical difference-frequency-generation sources. Mid-infrared dual-comb spectroscopy opens up unique opportunities to perform broadband spectroscopic measurements with high resolution, high requisition rate, and high detection sensitivity.

Mid-infrared methane detection in a photonic bandgap fiber using a broadband optical parametric oscillator

We demonstrate methane sensing using a photonic bandgap fiber-based gas cell and broadband idler pulses from a periodically-poled lithium niobate femtosecond optical parametric oscillator. The hollow core of the fiber was filled with a methane:nitrogen mixture, and Fourier transform spectroscopy was used to measure transmission spectra in the 3.15-3.35 mum methane absorption region. The method has applications in gas sensing for remote or hazardous environments and potentially at very low concentrations.

Adaptive beam profile control using a simulated annealing algorithm

We present a programmable beam-shaping method based on the combination of a deformable mirror membrane mirror and a simulated annealing algorithm. The algorithm iteratively adjusts the control voltages of 37 independent electrodes to reduce the variance between the chosen shape and the actual beam shape. The experimental results show that the system is capable of adaptively creating, on demand, Gaussian and super-Gaussian beam profiles that closely match the desired target parameters.

Mid-infrared gas sensing using a photonic bandgap fiber

We demonstrate methane sensing based on Fourier transform infrared spectroscopy using a hollow-core photonic bandgap fiber guiding in the mid-infrared and idler pulses from a femtosecond optical parametric oscillator. Transmission measurements are presented for several fibers, and sensing is demonstrated using a fiber whose bandgap overlaps the methane fundamental absorption lines. The gas filling process of the air core is described, and qualitative methane concentrations measurements to 1000 ppm (parts in 10(6)) are reported. Operation down to 50 ppm based on our current experiment is predicted.

Solid immersion lens applications for nanophotonic devices

Solid immersion lens (SIL) microscopy combines the advantages of conventional microscopy with those of near-field techniques, and is being increasingly adopted across a diverse range of technologies and applications. A comprehensive overview of the state-of-the-art in this rapidly expanding subject is therefore increasingly relevant. Important benefits are enabled by SIL-focusing, including an improved lateral and axial spatial profiling resolution when a SIL is used in laser-scanning microscopy or excitation, and an improved collection efficiency when a SIL is used in a light-collection mode, for example in fluorescence micro-spectroscopy. These advantages arise from the increase in numerical aperture (NA) that is provided by a SIL. Other SIL-enhanced improvements, for example spherical-aberration-free sub-surface imaging, are a fundamental consequence of the aplanatic imaging condition that results from the spherical geometry of the SIL. Beginning with an introduction to the theory of SIL imaging, the unique properties of SILs are exposed to provide advantages in applications involving the interrogation of photonic and electronic nanostructures. Such applications range from the sub-surface examination of the complex three-dimensional microstructures fabricated in silicon integrated circuits, to quantum photoluminescence and transmission measurements in semiconductor quantum dot nanostructures.