## 4 Hybrid Photonic/Millimetre-Wave System and Simulation Details  
### System Simulation  
The hybrid photonic/mm-wave platform is depicted in Figure 1. The system is simulated in Matlab and is designed to resemble the experimental setup presented in [11]. Table 1 gives the key simulation parameters. The optical portion of the system contains two optical sources that are simulated by way of the generation of two carriers separated by the mm-wave frequency (60 GHz), each with independently generated noise terms. The electric field associated with a simulated carrier is described using the general expression:  
\[E(t)=\sqrt{1+n_{RIN}}\cdot E_{0}\cdot\exp(j2\pi f_{c}t+\phi(t))\enspace. \tag{1}\]  
where \(E_{0}\) represents the optical field amplitude, \(f_{c}\) is the carrier frequency and \(n_{RIN}\) is the band-limited relative intensity noise (RIN), which is formulated as described in [5]. Moreover, \(\phi(t)\) contains the phase noise of the optical carrier. Its discrete form is implemented by taking \(m\) samples (where \(m\) is also the length, in samples, of the data signal to be transmitted) of a uniformly Gaussian distributed noise vector with zero mean and unity variance, \(\hat{f}(m)\), and performing a scaled running sum over the vector, such that the random walk phase noise at the \(l\)th time step is given by:  
\[\phi(l)=\sqrt{2\pi\cdot LW_{opt}\cdot t_{s}}\sum_{m=0}^{l}\hat{f}(m)\enspace. \tag{2}\]  
where \(LW_{opt}\) is the 3-dB optical linewidth and \(t_{s}\) is the sampling period, which was 5 ps in this work. The optical sources shown in Figure 1 both produce an optical carrier as per Equation (1), with each being assigned the same levels of independently generated (i.e., un-correlated) RIN and phase noise. The frequencies of the carriers were set within the simulation spectral window (\(\pm\)100 GHz), to have a frequency separation of 60 GHz. Partial single-sideband (SSB) modulation of one of the optical carriers with a real valued intermediate frequency (IF) OFDM/APSK signal is performed using a modelled Mach-Zehnder modulator (MZM), followed by an optical band-pass filter (OBPF), while the other carrier is unmodulated. The MZM is biased close to, but not on, the null point of its transfer characteristic. This provides optical field modulation, while allowing the optical carrier to remain relatively unsuppressed. Such operation is required by the PNC receiver stage, whose operation is described below. In practice, ideal optical SSB modulation is difficult to achieve at frequencies close to the carrier, if the carrier itself is to be maintained. This is replicated here by setting the OBPF (with passband of 5 GHz) such that the lower frequency sideband is suppressed by \(\sim\)25 dB relative to the upper sideband. All filtering in the simulated system is implemented using a Gaussian shaped profile applied in the frequency domain. The simulated spectra of the unmodulated and partial SSB modulated optical carriers are shown in Figure 2a,b, respectively. Figure 2a illustrates the Lorentzian-shaped spectral profile synonymous with optical carrier generation [33]. The optical carriers are combined and fed to a PIN photodetector with a bandwidth of 100 GHz and a shot and thermal noise as defined in [5]. Optical heterodyning of the modulated and unmodulated carriers takes place, producing an electrical signal with a strong carrier term at 60 GHz and information sideband signal at 62 GHz, as shown by the mm-wave spectrum in Figure 2c. Following V-band wave-guide filtering, the electrical signal can be directed to one of two sim  
Figure 1: Simulated hybrid photonic/mm-wave system setup diagram, including the phase noise cancelling analog receiver architecture. Figure 2: Simulated **(a)** Unmodulated optical carrier, **(b)** partial SSB modulated optical carrier and **(c)** mm-wave spectrum after photo-detection. Numbering corresponds to measurement points in Figure 2.  
1.