## 2 Principle  
The schematic diagram of the proposed ternary modulated microwave signals generator is shown in Figure 1i. A linearly polarized optical wave from a laser diode (LD) gets through a polarization controller (PC) and is sent to DP-DPMZM, which consists of a polarization beam splitter (PBS), two dual-parallel Mach-Zehnder modulators (DPMZMs), and a polarization beam combiner (PBC). The radio frequency (RF) signal is loaded on the Mach-Zehnder modulator1 (MZM1) and MZM2 of the main X-DPMZM, while the Y-DPMZM is driven by an electrical binary coding or single-chirp waveform from an arbitrary waveform generator (AWG). Then, the output of DP-DPMZM is send to the erbium-doped fiber amplifier (EDFA); after amplification, the light wave is split by the PBS. The two split signals from PBS are injected into a balanced photodetector (BPD) to perform square law detection. The spectrum of optical signal and microwave signal has been displayed in Figure 1 ii, and the modulation configurations of DP-DPMZM for generating ASK, PSK, and LFM signals are shown in Figure 1 iii-v.  
Figure 1: (i). Schematic diagram of proposed signals generators. LD, laser diode; PC, polarization controller; DP-DPMZM, dual-polarization dual-parallel Mach–Zehnder modulator; RF, radio frequency; AWG, arbitrary waveform generator; PBS, polarization beam splitter; PBC, polarization beam combiner; EDFA, erbium-doped fiber amplifier; BPD, balanced photodetector. (ii). Spectra at different points in subfigure (i). (iii). Amplitude modulation. (iv). Phase modulation. (v). Frequency modulation. In the X-DPMZM, the direct current (DC) biases of MZM1, MZM2, and the main MZM are, respectively, set at maximum transmission point (MATP), minimum transmission point (MITP), and quadrature transmission point (QTP). Assuming that the optical wave from LD is \(E_{\text{in}}(t)=E_{0}\exp(j\omega_{0}t)\), the output of X-DPMZM can be expressed as:  
\[ \begin{array}{ll}E_{x}(t)&=\frac{\sqrt{2}}{2}E_{0}e^{j\omega_{0}t}\left[e^{j \beta_{1}\cos\left(\omega_{s}t\right)}+e^{-j\beta_{1}\cos\left(\omega_{s}t \right)}+e^{j\beta_{2}\cos\left(\omega_{s}t\right)+j\pi/2}-e^{-j\beta_{2}\cos \left(\omega_{s}t\right)+j\pi/2}\right]\\ &=\frac{\sqrt{2}}{2}E_{0}e^{j\omega_{0}t}\left[\mathop{\sum}\limits_{m=-\infty }^{+\infty}J_{2m}(\beta_{1})e^{j2m\omega_{s}t}+\mathop{\sum}\limits_{n=-\infty }^{+\infty}J_{2n-1}(\beta_{2})e^{j\ (2n-1)\ \ \omega_{s}t}\right]\end{array}  \tag{1}\]  
where \(E_{0},\ \omega_{0}\) denote the amplitude, angular frequency of optical carrier, and \(J_{2m},\ J_{2n-1}\) are the \((2m)\)th-order and \(2(n-1)\)th-order first-kind Bessel function. \(\beta_{1}=\pi V_{\text{RF1}}/V_{\pi}\), \(\beta_{2}=\pi V_{\text{RF2}}/V_{\pi}\) indicate the modulation indexes of MZM1 and MZM2, where \(V_{\pi}\) is the half wave voltage. \(V_{RF}\) and \(\omega_{s}\) are the amplitude and angular frequency of RF signal. An OFC with 17 sidebands can be obtained by properly setting modulation indexes, such as \(\beta_{1}=6.38,\ \beta_{2}=5.31\), there is \(|J_{0}(\beta_{1})|\approx|J_{1}(\beta_{2})|\approx|J_{2}(\beta_{1})|\approx|J _{3}(\beta_{2})|\approx|J_{4}(\beta_{1})|\approx|J_{5}(\beta_{2})|\approx|J_{6} (\beta_{1})|\approx A\), and \(|J_{7}(\beta_{2})|\approx|J_{8}(\beta_{1})|\approx B\). The higher-order components are too small to be considered, then Equation (1) can be simplified as:  
\[ \begin{array}{ll}E_{x}(t)&=\frac{\sqrt{2}}{2}E_{0}e^{j\omega_{0}t}\left[ \mathop{\sum}\limits_{m=-4}^{4}J_{2m}(\beta_{1})\ e^{j2m\omega_{s}t}+\mathop{ \sum}\limits_{n=-3}^{4}J_{2n-1}(\beta_{2})\ e^{j\ (2n-1)\ \ \omega_{s}t}\right]\\ &=\frac{\sqrt{2}}{2}E_{0}e^{j\omega_{0}t}\left[A\mathop{\sum}\limits_{m=0}^{ 6}\cos(m\omega_{s}t)+B\mathop{\sum}\limits_{n=7}^{8}\cos(n\omega_{s}t)\right] \end{array}  \tag{2}\]  
The output signal \(Ex(t)\) of the X-DPMZM and the modulated light wave \(Ey(t)\) from the Y-DPMZM are injected into the PBS after amplification. The polarization axes of PBS have angles of 45\({}^{\circ}\) and 135\({}^{\circ}\)[23], the output signal can be written as:  
\[\left[