ABSTRACT
This chapter describes several types of integrated Laser Doppler velocimeters (LDVs) using the planar lightwave circuit (PLC) technology, especially, a wavelength-insensitive LDV and a multipoint LDV using arrayed waveguide gratings (AWGs). It focuses on two methods for two-dimensional velocity measurement using a simple optical configuration without any optical modulator. LDV have been widely used to measure the velocity of a fluid flow or rigid object in various research and industries since the introduction of the concept in 1964. Several approaches have been reported for directional discrimination without optical modulators, although these approaches are for one-dimensional velocity measurement. The AWG is one of the planar devices. Silica-based PLC technology has been used to fabricate waveguide devices including AWGs. The simulation was performed by assuming to use silica-based materials as the optical circuit. The optical circuit consists of input waveguides, two slab waveguides are waveguide array, and, output waveguides.
