InP-Based THz Beam Steering Leaky-Wave Antenna

Abstract

For mobile THz applications, integrated beam steering THz transmitters are essential. Beam steering approaches using leaky-wave antennas (LWAs) are attractive in that regard since they do not require complex feeding control circuits and beam steering is simply accomplished by sweeping the operating frequency. To date, only a few THz LWAs have been reported. These LWAs are based on polymer or graphene substrates and thus it is quite impossible to monolithically integrate these antennas with state-of-the-art indium phosphide (InP) based photonic or electronic THz sources and receivers. Therefore, in this paper, we report on an InP-based THz LWA for the first time. The developed and fabricated THz LWA consists of a periodic leaking microstrip line integrated with a grounded coplanar waveguide to microstrip line (GCPW-MSL) transition for future integration with InP-based photodiodes. For fabrication, a substrate-transfer process using silicon as carrier substrate for a 50 µm thin InP THz antenna chip has been established. By changing the operating frequency from 230 GHz to 330 GHz, the fabricated antenna allows to sweep the beam direction quasilinearly from-46° to 42°, i.e. the total scanning angle is 88°. The measured average realized gain and 3 dB beam width of a 1.5 mm wide InP LWA are ~11 dBi and 10°. This paper furthermore discusses the use of the fabricated LWA for THz interconnects. Index Terms-Beam steering, indium phosphide, leaky wave antenna, monolithic integrated circuits, wafer bonding. I. INTRODUCTION ERAHERTZ (THZ) waves feature distinct advantages compared to its neighboring spectra, making this frequency spectrum (0.1-10 THz) very attractive for several applications. THz waves are far less energetic than X-rays, i.e. they are nonionizing for biological tissues and, consequently, are promising for several medical applications [1-4]. Benefiting from the shorter wavelength in contrast to microwaves, THz waves offer a much higher spatial resolution which makes them quite intriguing for high-resolution imaging applications [5, 6]. Beyond the high spatial resolution, most dry dielectric materials are transparent for THz waves, whereas materials with high

The effect of angular dispersion on THz data transmission

“…If multiple angularly dispersive devices are placed in a channel, the affect will accumulate and could severely limit the spectral bandwidth at the receiver. In the case of effective beam-steering, the potential of using diffractive elements is an ongoing investigation 39 , 40 . The impact of such devices on the spectral bandwidth and any additional loss introduced must also be thoroughly considered.…”

THz Systems Exploiting Photonics and Communications Technologies

“…12(b) [105], [107]. Some other demonstrations used such THz LWAs for wireless communications [108], [109], but this encountered angle-dependent frequency & bandwidth use. One demonstration creatively used a fast-wave LWA for frequency (de)multiplexing in THz wireless communications [110].…”

Mobile Terahertz 6G Communications Enabled by Integrated Photonic-Assisted Beam Steering Antennas

“…The on-chip THz LWA is based on a microstrip transmission line with altogether 32 rectangular stubs, placed on both sides of the microstrip to produce fast waves which can be radiated [6]. A substrate-transfer technology using a silicon wafer as a mechanical carrier substrate is established in order to be able to fabricate the LWA on a 50µm thin InP substrate.…”

“…A substrate-transfer technology using a silicon wafer as a mechanical carrier substrate is established in order to be able to fabricate the LWA on a 50µm thin InP substrate. The thin InP substrate is necessary to reduce the number of surface wave modes and achieve a high antenna gain [6]. For probing the antennas, the LWAs are integrated with on-chip grounded coplanar waveguide to microstrip-line (GCPW-MSL) THz transitions.…”