Integrated all-pass filters for tunable dispersion and dispersion slope compensation

Dispersion Compensation in Optical Communication Link Using Apf’s

“…For different frequencies different architectures of the FBGs have to be introduced along the fiber link. EDC is rendered ineffective for WDM system since it is complex and also not a direct method of compensation as it involve the optical to electronic and electrical to optical conversions making the WDM communication slow which can't be tolerated in this growing world hence the need of all pass filters is realized by which the multiple channels can be compensated with a single device because of the periodic properties of the phase response of these filters [12][13][14][15].…”

“…By using a multistage filter where the parameters are chosen optimally for each stage, a constant dispersion (or any desired response) can be approximated over a large portion of the FSR, thus yielding a large bandwidth utilization factor [15]. It is critical to achieve the design values for these parameters, and fabrication-induced variations on the coupling ratios must be minimized.…”

“…Different wavelengths have different cumulative dispersions at the receiver, and a device capable of applying varying amounts of dispersion compensation to each channel is needed. Because of the large number of channels in dense wavelength-division-multiplexed (WDM) systems, periodic filters are advantageous compared to single channel devices which require a unique filter for every WDM channel [14], [15]. Tunable dispersion compensation filters are of two types:…”

“…The new all-pass filter architectures are shown in Fig.6 (a), (b) and (c). Fig 6. (a) Ring resonator all-pass filter with a fixed coupling ratio, and fully tunable ring resonator all-pass filters with (b) an asymmetric MZI and (c) a symmetric MZI [15].…”

“…(b), the MZI path lengths are different by a length ∆ L = π dsep where dsep is the separation of the MZI arms. The effective coupling is given by ke which can be set to zero at a given wavelength by choosing Φm appropriately [15]. Fig.…”