Ultracompact integrated polarizers using bent asymmetric coupled waveguides

Compact and efficient three-mode (de)multiplexer based on horizontal polymer waveguide couplers

A compact and efficient polymer three-mode (de)multiplexer with two cascaded waveguide directional couplers fabricated on the same substrate along the horizontal direction is proposed. Three waveguides formed two couplers, where two narrower waveguides were placed on either side of the central waveguide. By optimizing the core height and width, the two couplers can ensure that the E11x mode of the two narrower waveguides are highly coupled into the E21x and E31x modes of the central waveguide at a wavelength of 1310 nm. The structural size of the fabricated three-mode (de)multiplexer using ultraviolet (UV) lithography technology is in agreement with the designed value. The fabricated device, which is 35 mm long, exhibits coupling ratios of 98.07% and 95.43% for the two couplers, respectively. The insertion losses of the three waveguides are 5.23 dB, 8.58 dB, and 14.39 dB, respectively. The device can achieve the multiplexing of three modes in two dimensions, which can increase the channel capacity of optical communication.

Asymmetric Concentric Microring Resonator Label-Free Biosensors

A study of label-free silicon nitride asymmetric double-microring resonators is presented. The use of highly accurate 3D vector modal techniques permits an extensive exploration of the parameter space defining the architecture of the proposed device in the search for optimal geometries and reaching configurations not addressed in previous studies that had been limited to symmetrical configurations. Asymmetry, on the other hand, permits to access resonances that exploit the radiation-quenching properties of the structure in an optimal way. The analysis presented also includes the effect of absorption in the sensor aqueous cladding that is generally omitted. The results of the numerical survey indicate that the optimized geometries bring about a substantive performance improvement at small microring radii that are impractical for more conventional single-ring geometries due to the high radiation losses. Therefore, lower footprint devices, and a larger scale of integration, can be attained with the proposed structure.

Design and characterization of silicon nitride ultracompact integrated polarizers using bent asymmetric coupled waveguides

In this work, we report on the design, fabrication, and characterization of integrated ultracompact polarizers of a recently proposed type based on bent coupled optical waveguides. The devices have been implemented using deep etched silicon nitride waveguides and employing only basic standard fabrication steps.

Radiation in bent asymmetric coupled waveguides

A numerical study of the radiation in coupled bent waveguides is presented. Such arrangements of curved waveguides in reduced radiation-loss configurations can be used to enhance the quality factor of integrated microresonators. 3D full vector computations of the complex modal fields (and propagation constants) and the transient propagation effects have been performed. The results obtained agree qualitatively with former 2D finite-difference time-domain (FDTD) analyses. At the same time, the calculations presented meet the accuracy requirements for the design of practical implementations that are unattainable with 2D approaches.