On-chip Photonic THz Emitter with Integrated InGaAs UTC-PD and 2×2 MPA Array on SiC Substrate

This work presents an on-chip integration of a 2×2 inset-patch microstrip patch antenna (MPA) array with an InGaAs uni-traveling-carrier photodiode (UTC-PD) on a silicon carbide (SiC) substrate, addressing the power-hungry issue of photonic THz sources. The absolute output power of an individual UTC-PD was enhanced using a high-thermal-conductivity SiC substrate via flip-wafer bonding, while the MPA array improved power efficiency, particularly in the broadside direction. Measurements demonstrated significant gains at 270 GHz and 290 GHz, with a 3 dB bandwidth of 10 GHz. E-field radiation patterns at 270 GHz and 300 GHz showed exceptional directivity and a narrowed beamwidth of 60 degrees, underscoring the array's directional emission capabilities and the on-chip THz emitter's potential for next-generation wireless THz communication systems.