在对中国工程物理研究院高功率太赫兹(THz)自由电子激光(FEL)装置理论分析和设计的基础上，针对目前THz FEL光腔设计面临的主要难点，提出了椭圆型耦合输出光腔的设计方案，并对椭圆型耦合输出光腔代替传统FEL光腔的优势、光腔品质、耦合效率等进行了分析研究。研究表明，椭圆型耦合光腔的设计更适合目前THz FEL波导光腔的光斑特点，可使光腔输出功率提高33%以上，输出耦合效率即光腔品质可提高30%~70%;随着辐射频率的提高，椭圆孔耦合输出光腔的优势提高更为明显。

The scheme of elliptical hole-coupling optical resonator is proposed instead of circular hole-coupling resonator which is used in THz FEL in order to increase the output power and resonator quality. Three-dimensional simulations and design on elliptical hole-coupling optical resonator are carried out using our 3D OSIFEL code. It is proved that the elliptical hole-coupling optical resonator is effective and applicable for the THz FEL. Using elliptical hole-coupling optical resonator, the output power can be increased by more than 33%, and the coupling efficiency of resonator can be increased almost by 30%-70%. The superiority of elliptical hole-coupling optical resonator will be more prominent with radiation frequency increasing.