Details

Autor(en) / Beteiligte

• Nguyen, Truong Khang
• Kim, Won Tae
• Kang, Bong Joo
• Bark, Hyeon Sang
• Kim, Kangho
• Lee, Jaejin
• Park, Ikmo
• Jeon, Tae-In
• Rotermund, Fabian

Titel

Photoconductive dipole antennas for efficient terahertz receiver

Ist Teil von

• Optics communications, 2017-01, Vol.383, p.50-56

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2017

Quelle

Access via ScienceDirect (Elsevier)

Beschreibungen/Notizen

• We designed various photoconductive antennas applicable to efficient terahertz (THz) receivers and experimentally investigated their detection characteristics. Three different antennas based on Grischkowsky (H-), I-, and bowtie shapes were fabricated on a 1.2-μm-thick low-temperature GaAs layer that was grown on a semi-insulating GaAs substrate and subsequently attached to extended hemispherical silicon lenses. The experimental results showed different characteristics for detection responsivity and agreed well with the theoretical prediction. Measurements of the peak-to-peak amplitudes of the detected THz photocurrent were approximately 67, 42, and 59nA for the H-shaped, I-shaped, and bowtie-shaped antennas, respectively. The I- and bowtie-shaped antennas provided higher THz detection sensitivities than the H-shaped antenna in the low-frequency region, i.e., below 0.6THz. At a frequency of 0.2THz, the I- and bowtie-shaped antennas offered an approximately 3.6-fold and 6-fold enhancement, respectively, in THz detection sensitivity compared to the H-shaped antenna. The bowtie-shaped antenna produced better peak amplitude and a wider spectral bandwidth than the I-shaped antenna. The observed detection peak frequencies of the I-shaped and bowtie-shaped antennas possessing very long dipole arms indicate that the lowest limit of the frequency detected in a typical THz-TDS using a GaAs photoconductive antenna as emitter/detector is around 0.2THz. •We analysis, design, and characterization of three prototypes of photoconductive antennas namely Grischkowsky (H-shaped dipole) (Auston switch dipole), an I-shaped (stripline dipole), and a bowtie photoconductive antenna.•A "hybrid" numerical and analytical procedure for estimating the currents induced on the antenna and in the gap, when operating in the reception, is also discussed. The experimental results, which was obtained by a THz time-domain spectroscopy system, show different spectral detection responsivity and agree with the theoretical prediction.•The experimental results show that the I-shaped and bowtie-shaped antennas could detect THz signals at low-frequency regions below 0.6 THz with a much higher sensitivity than the H-shaped antenna. Therefore, these two antennas could be promising for the sensitive room-temperature detection of THz radiation in the low THz frequency region or in THz wireless communication systems.•The observed detection peak frequencies of the I-shaped and bowtie-shaped antennas possessing very long dipole arms indicate that the lowest limit of the frequency detected in a typical THz-TDS using a GaAs photoconductive antenna as emitter/detector is around 0.2 THz which has not been stated elsewhere.•This study provides a good recommendation in THz output power improvement by tuning the frequency response of the antenna toward the frequency response of the photoconductive material for an enhanced coupling of THz radiation to antenna.