Terahertz frequency measurement of far-infrared laser with an improvement of Martin–Puplett interferometer

In this paper, we present an improvement of Martin–Puplett interferometer (MPI) for terahertz frequency measurement, in which flat mirrors replace the roof ones. To understand the function of the improved MPI, its basic principle is described and the characteristics of electric field are analyzed. With the improved MPI, the operation frequency of a far-infrared laser is conveniently measured, and the experimental result is in good agreement with that of the far-infrared laser theoretical reported.