Ishizawa A, Nishikawa T, Goto T, Hitachi K, Sogawa T, Gotoh H
NTT Basic Research Laboratories, Nippon Telegraph and Telephone Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
Tokyo Denki University, Department of Electrical and Electronic Engineering, 5 Senjyu-Asahi-cho, Adachi-ku, Tokyo 120-8551, Japan.
Sci Rep. 2016 May 17;6:24621. doi: 10.1038/srep24621.
Low-noise millimetre-wave signals are valuable for digital sampling systems, arbitrary waveform generation for ultra-wideband communications, and coherent radar systems. However, the phase noise of widely used conventional signal generators (SGs) will increase as the millimetre-wave frequency increases. Our goal has been to improve commercially available SGs so that they provide a low-phase-noise millimetre-wave signal with assistance from an electro-optics-modulator-based optical frequency comb (EOM-OFC). Here, we show that the phase noise can be greatly reduced by bridging the vast frequency difference between the gigahertz and terahertz ranges with an EOM-OFC. The EOM-OFC serves as a liaison that magnifies the phase noise of the SG. With the EOM-OFC used as a phase noise "booster" for a millimetre-wave signal, the phase noise of widely used SGs can be reduced at an arbitrary frequency f (6 ≦ f ≦ 72 GHz).
低噪声毫米波信号对于数字采样系统、超宽带通信中的任意波形生成以及相干雷达系统都很有价值。然而，随着毫米波频率的增加，广泛使用的传统信号发生器（SGs）的相位噪声会增大。我们的目标是改进市售的信号发生器，使其在基于电光调制器的光学频率梳（EOM - OFC）的辅助下提供低相位噪声的毫米波信号。在此，我们表明，通过使用EOM - OFC弥合千兆赫兹和太赫兹范围之间的巨大频率差，可以大大降低相位噪声。EOM - OFC充当放大信号发生器相位噪声的联络器。将EOM - OFC用作毫米波信号的相位噪声“增强器”，可以在任意频率f（6 ≤ f ≤ 72 GHz）下降低广泛使用的信号发生器的相位噪声。
