Publications by authors named "Koen Alexander"

Article Synopsis
  • The study investigates how the unique properties of nanowires, particularly their large index contrast and small transverse dimensions, create strong electric field components that enhance second harmonic generation.
  • Through full-vectorial calculations, an efficiency map for nonlinear conversion is developed, highlighting various waveguide dimensions and orientations that can effectively convert a fundamental quasi-TE pump mode at 1550 nm into a higher-order second harmonic mode.
  • The findings suggest that III-V wire waveguides have promising capabilities for efficient nonlinear optical applications, especially in telecommunications.
View Article and Find Full Text PDF

Silicon nitride (SiN) is emerging as a competitive platform for CMOS-compatible integrated photonics. However, active devices such as modulators are scarce and still lack in performance. Ideally, such a modulator should have a high bandwidth, good modulation efficiency, low loss, and cover a wide wavelength range.

View Article and Find Full Text PDF

Recently, we have theoretically demonstrated that optically injected microdisk lasers can be tuned in a class I excitable regime, where they are sensitive to both inhibitory and excitatory external input pulses. In this paper, we propose, using simulations, a topology that allows the disks to react on excitations from other disks. Phase tuning of the intermediate connections allows to control the disk response.

View Article and Find Full Text PDF

We demonstrate class I excitability in optically injected microdisk lasers, and propose a possible optical spiking neuron design. The neuron has a clear threshold and an integrating behavior, leading to an output rate-input rate dependency that is comparable to the characteristic of sigmoidal artificial neurons. We also show that the optical phase of the input pulses has influence on the neuron response, and can be used to create inhibitory, as well as excitatory perturbations.

View Article and Find Full Text PDF