Tunable optical filters using compound ring resonators for DWDM

Abstract

Abstract-The device is based on a loop mirror in a ring resonator. The loop mirror allows tuning by changing the coupling coefficient of a directional coupler. The loop mirror is implemented using a Sagnac configuration to have the same optical path between the signals to be interfered (copropagating and counterpropagating ones). The filter structure allows optical integration for having higher free-spectral ranges. Simple design equations for the filter parameters and the tuning are reported. Measurements on a passive optical fiber tunable filter are presented. There is a good agreement between measurements and theory.

A Hybrid Electrooptic Microring Resonator-Based $1 \times 4\times 1$ ROADM for Wafer Scale Optical Interconnects

“…The relationship of index change , to the applied field , is dependent upon the electrooptic coefficient of the material and can be expressed as (1) where is the original index of refraction and is the index of refraction as a function of the applied electric field [15]. Given a cladding with relatively modest activity of 100 pm/V and a refractive index of 1.73, it is possible to estimate [using (1)] that the cladding will change in index by 0.0026 with the application of a 10-V m electric field.…”

“…Given a cladding with relatively modest activity of 100 pm/V and a refractive index of 1.73, it is possible to estimate [using (1)] that the cladding will change in index by 0.0026 with the application of a 10-V m electric field.…”

“…APIDLY tunable electrooptic (EO) Mach-Zehnder interferometers, resonant cavity microring resonator filters, and photonic bandgap crystal devices have been proposed as high speed optical interconnects for modulating and switching radio-frequency analog and digital optical signals in many commercial and military applications [1], [2]. Modulators made using inorganic EO materials such as silicon, gallium arsenide, and lithium niobate have recently demonstrated up to 50 GHz modulation speeds; however, these devices continue to be performance limited due to intrinsically low EO activities, relatively slow (e.g., picoseconds) response times, and high velocity mismatch between electrical and optical waves [3], [4].…”

Sagnac loop in ring resonators for tunable optical filters

“…The use of a Sagnac interferometer as the reflective element [20] alleviates this problem, because of its common-path architecture. This configuration is experimentally tested in its passive form in [21]. In any of these configurations, it is necessary to have a variable coupling coefficient, and its accuracy and tolerances must be analyzed.…”

“…Simple closed-form formulas describing the novel tuning process are derived in its active and passive configurations, along with the requirements for having a certain operation as a bandpass 0733-8724/$20.00 © 2005 IEEE or bandstop filter. Measurements on a fiber-optic prototype validating the theoretical model, and the tunability, are reported elsewhere [21]. Coupling coefficient tolerance effect, in terms of tuning capabilities, is also analyzed.…”