Millimeter-Wave and Terahertz-Wave Applications Enabled by Photonics

300-GHz-band wireless communication using a low phase noise photonic source

“…Terahertz communication is a hot topic for its potential to be applied in the next generation of wireless technology, considering the dramatically increased needs of the higher data rate and the extremely broad spectral available bandwidth in the terahertz region. Currently the carrier frequency at over 275 GHz was not allocated for any exclusive application, hence the research with the use of carrier frequencies at around 300 GHz has become very active [1][2][3][4][5][6][7][8][9][10]. It is not only because of its wide bandwidth of several tens of GHz makes, but also due to the rapid development of electronic and photonic devices.…”

“…The highest single-channel data rate achieved with an error-free condition, i.e., a bit error rate (BER) of less than 10 11 , is 50 Gbit/s with the on-off keying (OOK) modulation using a photonics-based broadband transmitter and a direct diode-detection receiver at 300 GHz [1]. However, due to the hardware limitations on bandwidth and/or sensitivity, it is difficult to further improve the data rate without any significant breakthrough on current devices.…”

“…While for the real-time communication, the phase noise of the carrier and/or local oscillator (LO) signal is a critical factor that determines the BER for these multi-level modulation systems [2,[8][9][10]. The optical frequency comb generator (OFCG) has been efficiently employed to stabilize both the frequency and phase in the transmitter compared with simple laser pair [1,2,11]. However, it is no longer effective for high-level modulation with a carrier frequency at 300-GHz band, since the signal generation scheme is essentially a frequency multiplication, in which the phase noise increases quadratically with the harmonic number [2].…”

Terahertz Sensor Using Photonic Crystal Cavity and Resonant Tunneling Diodes

“…Therefore, like radio waves they can penetrate materials, and like light waves they have a high directionality. Unique potential applications of THz waves, such as spectroscopic sensing, nondestructive imaging, and broadband communications, have been developed [1][2][3]. Especially, sensing applications are attracting much attention in the fields of biology, medicine, chemistry, physics, environment monitoring, and material science [4][5][6].…”

“…Previously, we have reported on the integration of RTDs with a PC slab for THz communication [3,28,31]. Here, we propose a compact-integrated THz sensing module based on a PC slab and RTDs as shown in Fig.…”