Terahertz spectrum analyzer based on a terahertz frequency comb

Abstract

Precision frequency measurements of terahertz (THz) waves are required to establish metrology in the THz spectral region. However, frequency measurement techniques in this region are immature. We propose a THz spectrum analyzer to measure the absolute frequency and spectral shape of continuous-wave THz waves. Based on a stable frequency comb generated in a photoconductive antenna, the absolute frequency of a sub- THz test source was determined at a precision of 2.8 x 10(-11). Furthermore, the spectral bandwidth of the THz spectrum analyzer can be extended over 1 THz, as demonstrated by measurement of a THz test source. This spectrum analyzer has the potential to become a powerful tool for THz frequency metrology.

Observation of 200th harmonic with fractional linewidth of 10−10 in a microwave frequency comb generated in a tunneling junction

“…Others have generated MFC with step-recovery diodes (SRD) 25 and non-linear transmission lines (NLTLs), 26 as well as using PD 27,28 and other methods that require lasers. 29,30 Both SRD and NLTL are used in low-noise applications.…”

“…26 PDs are also used in low-noise applications, 32 and a terahertz spectrum analyzer was based on a frequency comb generated with a PD. 27 Other methods for generating microwave frequency combs that require lasers include optoelectronic feedback by injecting the optical pulses to a slave laser, 29 and coupling the detected microwave output to a microwave synthesizer for negative feedback. 30 Nevertheless, the measured linewidth of the harmonic signal generated with each of these methods is typically greater than 1 kHz.…”

Absolute Intensity Measurements of CW GHz and THz Radiation Using Electro-Optic Sampling

“…The experimental technique is based on the concept of THz frequency combs [2], [3], [12], [13] that are obtained from optical frequency combs [14]. Although we employ this technique for the measurement of CW GHz/THz signals, it can also easily be applied to the measurement of pulsed THz signals.…”

High-Speed High-Resolution Terahertz Spectrometers

“…Also, terahertz frequency comb spectroscopy (TFCS) has been recently demonstrated through generation and detection of a THz frequency comb [18,19]. The THz frequency comb has many attractive features for frequency metrology, such as high accuracy, broadband selectivity, and ultranarrow linewidth.…”