Detachable Deep Ultraviolet Fiber Optic Vacuum Feedthrough Structure

Charge management in space gravitational wave detection relies on utilizing the photoelectric effect of deep ultraviolet light to neutralize stray charges on the inertial sensor's surface. A pivotal component for this task is the vacuum feedthrough, facilitating the introduction of the deep ultraviolet fiber while maintaining the vacuum integrity of the inertial sensor. This paper proposes a detachable vacuum fiber feedthrough structure, featuring a stepped countersink design in the metal housing to securely couple with the bare deep ultraviolet fiber. The seal between the metal housing and the flange is achieved through internal screw compression of the flexible material. The design of the vacuum fiber feedthrough structure is detailed, and its performance is evaluated by measuring the overall structure leakage rate using helium mass spectrometry and the optical transmission loss with an optical power meter. Experimental results indicate a vacuum leakage rate of less than 1.0 \times 10⁻¹² Pa \cdotm³ \cdots⁻¹ for the designed feedthrough structure, with an optical power loss of less than 0.5 dB when transmitting deep-ultraviolet light. These findings demonstrate the suitability of the proposed structure for meeting the charge management requirements of both ground-based and space-based gravitational wave detection experiments, ensuring the normal operation of gravitational wave detection.