Photonic microwave tunable single-bandpass filter based on a Mach-Zehnder interferometer

Harmonic distortion in microwave photonic filters

“…3. In this case, note that the fundamental electrical transfer function has a single bandpass centered at the designed frequency f o = 4.56 GHz since the optical source has a gaussian profile sliced with a sinusoidal pattern [12]. Note that this filter is more selective as compared to the previous case and, therefore, it is expected that the nonlinear electrical responses have a different behaviour.…”

“…Also, we experimentally show the harmonic distortion of two different microwave photonic filtering structures which are based on the slicing of a broadband source (BBS) combined with a dispersive single mode fiber (SMF) link. We consider a discrete slicing achieved by a structure of AWGs obtaining a periodical electrical response [9] and a quasi-continuous slicing by means of a Mach-Zenhder Interferometer (MZI) yielding a non-periodic response [12]. The experimental and theoretical analysis of these electrical responses yield an excellent agreement revealing the interest of considering this harmonic distortion model on the design of advanced microwave photonic filters to exploit the MWP benefits.…”

“…In either case, the implemented filters present a periodic spectral response with multiple passbands. However, a single bandpass filtering response can be achieved with structures based on phase-to-intensity conversion [10] and continuous time impulse response [11,12]. Most of the reported work on MWP filters focus exclusively on their linear behavior, assuming small signal operation, but it is a fact, as with any filtered microwave photonic link, that nonlinearities are to be expected in the form of harmonic contributions to the filter overall transfer function.…”

Highly chirped single-bandpass microwave photonic filter with reconfiguration capabilities

“…Phase dependence can be developed by means of a Taylor expansion around the central frequency of the optical source ω 0 [16]:…”

Wide-range continuously tunable microwave photonic filter using high-birefringence linearly chirped fiber Bragg grating and polarization beamsplitters

“…To satisfy the requirement of incoherent summing, either the laser coherence time must be shorter than the optical delay time, or the state of polarization ͑SOP͒ of the optical signals must be orthogonal. For the first approach, a laser array 3 or a sliced wideband source 4 is used, but these increase the complexity of the system. If a single-wavelength laser source is used, either a long time delay line is required, 5 which restricts the free spectral range ͑FSR͒, or the optical mixing effect is used, 6 which increases the system cost.…”