Photonic generation of a parabolic-shaped microwave signal and dual-linear-chirp microwave waveform
Ritesh Kumar, Sanjeev Kumar Raghuwanshi
Abstract
Based on an external modulation technique through a dual-polarized dual-parallel Mach–Zehnder modulator, a photonic technique is proposed for the generation of a microwave signal with a parabolic shape. An optically modulated waveform from the modulator is passed through an optical bandpass filter, which results in parabolic signals of 1 GHz and 9 GHz frequencies at the photo detector. A peak power spectral component of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>−</mml:mo> </mml:mrow> <mml:mn>30</mml:mn> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">d</mml:mi> <mml:mi mathvariant="normal">B</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> power is obtained at 1 GHz and 9 GHz frequencies of the parabolic signal. Based on the present methodology, a parabolic signal of the desired frequency band can be obtained. The obtained signal is processed to generate a dual-linear-chirp signal by passing through the phase modulator. Here, a dual-linear-chirp microwave waveform with a chirp rate of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mn>1.53</mml:mn> <mml:mi mathvariant="normal">Π</mml:mi> <mml:mo>×</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>19</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">H</mml:mi> <mml:mi mathvariant="normal">z</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> </mml:math> is achieved at 6 GHz center frequency. The results are obtained through MATLAB simulation and verified by experimental results. A fair agreement is found between the result obtained through MATLAB simulation and the result obtained by experimental verification.