# Advances in High-Speed, High-Power Photodiodes: From Fundamentals to Applications
## 4 Photodiode Photonic-Integrated Applications
### Photodiodes Integrated with Antennas
Figure 29d shows the frequency response at different quasi-fields in the non-depleted absorber, while the W\({}_{\text{an}}\), W\({}_{\text{ad}}\) and W\({}_{\text{dep}}\) are separately  
Figure 26: InP–based PIN–PD integrated with four bowtie antennas and mounted on Si–lens to increase emitted power and high directivity [206]. **(a)** The fabricated InP chip and the schematic for packaging of the antenna array; **(b)** the emitter chip module; and **(c)** measurement setup. 0.12 \(\upmu\)m, 0.06 \(\upmu\)m, and 0.18 \(\upmu\)m. The 3-dB bandwidth is enlarged from 603 to 1087 GHz with the increase in quasi-field from 10 to 30 kV/cm. Figure 28: Traveling–wave UTC–PD (TW–UTC–PD) integrated with resonant, bowtie, and log–periodic antennas, and the radiated power at different photocurrent levels for resonant antenna (**a**), and for bowtie and log–periodic antennas (**b**), where the device dimensions are in \(\upmu\)m\({}^{2}\)[21; 222]. Figure 27: **(a)** THz UTC–PD chip integrated with twin–diploe antenna using impedance matching circuit and (**b**) the output power versus different frequency [209]. **(c)** Adaptive THz beam steering in fiber–coupled UTC–PD array chip to generate THz wave [211; 212; 213]. The MUTC-PD is integrated with a bowtie antenna shown in Figure 29b, where Si-lens (Figure 29c) is employed to increase the output power. Being accompanied by a well-designed matching circuit and the rectangular waveguide output port, the quasi-optical antenna-integrated photomixer module can be completed as shown in the inset of Figure 29e. It can be seen that the measured output power gradually decreases with the increase in the frequency while the typical values are larger than \(-20\) dBm at \(300\) GHz, \(-30\) dBm at \(1\) THz, and approximately \(-40\) dBm at \(2\) THz. Furthermore, the calculated results which changed with the different effective electron velocities are also shown in Figure 20e, as comparisons with the measured values. Parts of PDs photonic-integrated antennas [18, 21, 22, 25, 72, 91, 98, 123, 124, 134, 142, 204, 205, 206, 208, 209, 223, 224, 225, 226, 227] are summarized in Figure 24.0 \begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Device Type \({}^{\star}\)** & **Coupling Type** & **Si Lens** & \(I_{ph}\) **(mA)** & **Output Power (dBm)** & **Ref.** \\ \hline NBUTC-PD & Yagi antenna & No & \(30\) & \(-14.1\) (\(25.7\) mW) @ \(100\) GHz & [18, 223] \\ \hline TW-UTC-PD & Log-periodic antenna & No & \(9\) & \(-11.5\) (\(70\)\(\mu\)W) @ \(150\) GHz & [21] \\ \hline TW-UTC-PD & Bowtie antenna & No & \(13\) & \(-9.79\) (\(105\)\(\mu\)W) @ \(255\) GHz & [21] \\ \hline TW-UTC-PD & Resonant antenna & No & \(10\) & \(-8.3\) (\(148\)\(\mu\)W) @ \(457\) GHz & [21] \\ \hline TW-UTC-PD & Bowtie antenna & No & \(13\) & \(-20\) (\(10\)\(\mu\)W) @ \(612\) GHz & [21] \\ \hline TW-UTC-PD & Resonant antenna & No & \(10\) & \(-16.2\) (\(24\)\(\mu\)W) @ \(914\) GHz & [21] \\ \hline CC–MUTC-PD & Log-periodic antenna & Yes & \(7\) & \(9.9\) (\(9.77\) mW) @ \(70\) GHz & [22] \\ \hline CC–MUTC-PD & Sinuous antenna & Yes & \(7\) & \(11.5\) (\(14.13\) mW) @ \(90\) GHz & [22] \\ \hline CC–MUTC-PD & Sinuous antenna & Yes & \(20\) & \(20\) (\(100\) mW) @ \(90\) GHz & [22] \\ \hline CC–MUTC-PD & Spiral antenna & Yes & \(7\) & \(8.8\) (\(7.59\) mW) @ \(100\) GHz & [22] \\ \hline MUTC-PD & Vivaldi antennas & No & \(10\) & \(5\) (\(3.2\) mW) @ \(110\) GHz & [25] \\ \hline Hybrid absorber UTC-PD & Bowtie antenna & Yes & \(6\) & \(-20\) (\(10\)\(\mu\)W) @ \(300\) GHz & [72] \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The comparisons of emitted power for PDs integrated with antennas. Figure 29: Hybrid absorber UTC–PD (modified UTC–PD, MUTC–PD) integrated with bowtie antenna [72].