One-dimensional (1-D) deep-etched gratings on aspecially grown AlGaAs wafer were designed and fabricated.The gratings were fabricated using state-of-the-art electron beamlithography and high-aspect-ratio reactive ion etching (RIE) inorder to achieve the required narrow deep air slots with goodaccuracy and reproducibility. Since remarkable etch depths (up to1.5 μm), which completely cut through the waveguide core layer,have been attained, gratings composed of only five periods (and,thus, shorter than 6 μm) have a bandgap larger than 100 nm. A defectwas introduced by increasing the width of the central semiconductortooth to create microcavities that exhibit a narrowtransmission peak (less than 7 nm) around the wavelength of1530 nm. The transmission spectra between 1460 and 1580 nmhave been systematically measured, and the losses have been estimatedfor a set of gratings, both with and without a defect,for different periods and air slot dimensions. Numerical resultsobtained via a bidirectional beam propagation code allowed theevaluation of transmissivity, reflectivity, and diffraction losses.By comparing experimental results with the authors’ numericalfindings, a clear picture of the role of the grating’s geometricparameters in determining its spectral features and diffractivelosses is illustrated.
展开▼
