We present a high-performance optical phased array on a double-layer Si3N4 platform, which takes the advantages of low macroscopic stress and low loss. We have performed both analytical and numerical simulations. In our design, the full width at half-maximum (FWHM) of the main lobe in transversal direction is 0.08°, while the FWHM in longitudinal direction is 0.09° due to the shallow etched grating antennas. The upward power is more than 50% in a broad wavelength range by optimizing the cladding thickness. The grating lobe suppression is reduced to 8.8 dB by using wide waveguide grating antennas. This optical phased array with high resolution and high efficiency will have a wide application in the fields of LIDAR and unmanned vehicles.
Dynamically tuning Q factor in optical resonators is now more feasible in information processing applications, such as light storage and wavelength conversion. This paper proposed and demonstrated a new dynamically tuning Q approach that is realized in coupled two rings structure. One resonator uses an add-drop configuration, coupled to another single micro-ring. The heating causes an increase in the refractive index, which in turn causes resonant wavelength redshift. This shift is a switch to control the coupling between the two rings, to tune the linewidth of light confined in the ring, equivalent to tune the quality factor. And we adjust the detuning and coupling state between the two rings to control the light coupled into the resonator. The Q factor decreases from 56,525 to 16,450 in the transmission spectrum with the different heater power. In this way, we successfully realized a modulation of the Q from high to low states in the structure. Besides, the original coupling spacing between the two rings also has an influence on the Q factor. The larger the coupling spacing, the higher the Q factor. In addition, we also study the changes of phase and delay time in the tunable process. The results show that the change of fast light (high Q) and slow light (low Q) can be realized at the same time, which would enable applications for on-chip adjustable time delay, fast/slow light and light storage.
Telecentric lenses have been used for high-precision visual measurement systems because of their unique imaging properties, whereas the principal point is usually not considered in the projection model for calibration. Here, we propose an improved model containing the principal point for calibrating telecentric cameras. Detailed mathematical derivation from the pinhole model is performed. Then, an experimental setup is established. Two different telecentric cameras are used for verification. The results prove that calibrating telecentric cameras based on the improved model considering the principal point can achieve up to 55.37% higher accuracy and better stability than the common projection model without the principal point.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.