Active Integrated Filters for RF-Photonic Channelizers

Abstract

A theoretical study of RF-photonic channelizers using four architectures formed by active integrated filters with tunable gains is presented. The integrated filters are enabled by two- and four-port nano-photonic couplers (NPCs). Lossless and three individual manufacturing cases with high transmission, high reflection, and symmetric couplers are assumed in the work. NPCs behavior is dependent upon the phenomenon of frustrated total internal reflection. Experimentally, photonic channelizers are fabricated in one single semiconductor chip on multi-quantum well epitaxial InP wafers using conventional microelectronics processing techniques. A state space modeling approach is used to derive the transfer functions and analyze the stability of these filters. The ability of adapting using the gains is demonstrated. Our simulation results indicate that the characteristic bandpass and notch filter responses of each structure are the basis of channelizer architectures, and optical gain may be used to adjust filter parameters to obtain a desired frequency magnitude response, especially in the range of 1–5 GHz for the chip with a coupler separation of ∼9 mm. Preliminarily, the measurement of spectral response shows enhancement of quality factor by using higher optical gains. The present compact active filters on an InP-based integrated photonic circuit hold the potential for a variety of channelizer applications. Compared to a pure RF channelizer, photonic channelizers may perform both channelization and down-conversion in an optical domain.

Photonics for microwave measurements

“…Multiple laser sources, modulators, amplifiers, couplers, resonators, gratings, and PDs can be integrated on a monolithic chip of the size of a square millimeter or less. As an example, a photonic microwave channelizer comprised of active integrated filters was fabricated on a single chip on InP wafer with a size of ∼9 mm for coupler separation , with the assistance of microelectronic processing techniques. Integrated lenses, resonators, and nonlinear waveguides have also been employed to perform spectrum analysis and IFM [, ].…”

Analysis of a Polynomial System Arising in the Design of an Optical Lattice Filter Useful in Channelization

“…In principle, these coefficients can vary from coupler to coupler. In this work we take them to be the same, since in the results reported in [1], this was in force (see [1] also, however, for the state space description when these coefficients can vary from coupler to coupler).…”

“…The study in [1] showed that the gains can be used to tune the behavior of the filter. The selection of gains in [1], however, was somewhat ad hoc.…”

“…The selection of gains in [1], however, was somewhat ad hoc. In this paper we lay the foundations of a more systematic study.…”

“…Remark 3.1 Of the four structures considered in [1], three had even characteristic polynomials. For two of those, we have mathematical explanations for this evenness.…”