- 1. 中国科学院上海微系统与信息技术研究所，中国科学院太赫兹固态技术重点实验室，上海 200050
- 2. 中科院上海微系统与信息技术研究所
- 3. 中国科学院上海微系统与信息技术研究所
Research progress of terahertz semiconductor optical frequency combs
- Received Date:
16 March 2020
Abstract: The optical frequency comb consists of a series of equally spaced and highly stable frequency lines. Due to the advantages of the ultra-high frequency stability and ultra-low phase noise, optical frequency combs have important applications in precision spectrum measurement, imaging, communications and other fields. In the terahertz frequency range, semiconductor-based electrically pumped terahertz quantum cascade lasers have the characteristics of high power output and wide frequency coverage, and are the ideal carriers for generating terahertz optical frequency combs. This article first briefly introduces the progress of the optical frequency comb in the communication band and the mid-infrared band, and discusses its research results in these two band. Then it mainly introduces the research progress of the optical frequency comb based on the terahertz semiconductor quantum cascade laser, and details the methods of generating the optical frequency comb in the free-running, active frequency stabilization and passive frequency stabilization modes. Among them, in the free running mode, the optical frequency comb is not stable enough, and the large dispersion limits the spectrum width. Therefore, the dispersion compensation of the device (design and optimization of the active area) is one of the important factors to improve the performance of the laser, stabilize the optical frequency comb, and broaden the spectral bandwidth. At present, the active frequency stabilization mode is a relatively mature method to realize the optical frequency comb. In addition, based on the optical frequency comb, this article also details the methods and applications of generating two optical combs using two terahertz quantum cascade lasers (including on-chip dual optical combs and separating dual optical combs) and comparative analysis their advantages and disadvantages. Dual-comb spectroscopy can overcome the problems that traditional terahertz spectrometers require a mechanical scanning system and it is difficult to achieve real-time spectral detection. And compared with Fourier transform infrared spectroscopy, it has advantages in fast data acquisition and high spectral resolution, which is the main direction of optical frequency comb application. The emergence of dual optical combs not only verified the concept of optical frequency combs, but also further promoted the development of optical frequency combs, and improved the dynamic range, spectral width, and output power of lasers.