The port fraction in an integrating cavity is defined as the ratio of the area of all the leaky ports to the total internal surface area of the cavity. It allows for the regulation of the cavity’s output radiation flux, thereby influencing the formed light field within the cavity. Building upon this fundamental parameter, we present a technique for determining the effective optical path length (EOPL) of an integrating cavity by examining the output light's variation as a function of port fraction. A relationship between the EOPL and cavity parameters has been established without the presence of gas absorption. To corroborate the method, we calculated the EOPL of the cavity at 764 nm employing both our proposed method and the gas absorption-based approach. Upon comparison, it was observed that the two methods yielded consistent EOPL results, specifically 109.5 (2) cm and 109 (2) cm, respectively. This study demonstrates that the output light from an integrating cavity indeed conveys information about its EOPL in the absence of gas absorption. This insight holds significant value for determining the EOPL of integrating cavities as well as other optical cavity types.

积分腔中的端口分数定义为所有泄漏端口的面积与腔的总内表面积的比率。它可以调节腔的输出辐射通量，从而影响腔内形成的光场。在此基本参数的基础上，我们提出了一种通过检查输出光随端口分数的变化来确定积分腔有效光程长度 (EOPL) 的技术。在不存在气体吸收的情况下建立了 EOPL 和腔参数之间的关系。为了验证该方法，我们采用我们提出的方法和基于气体吸收的方法计算了 764 nm 腔的 EOPL。经过比较，发现两种方法产生了一致的 EOPL 结果，分别为 109.5 (2) cm 和 109 (2) cm。这项研究表明，在没有气体吸收的情况下，积分腔的输出光确实传达了有关其 EOPL 的信息。这一见解对于确定积分腔以及其他光学腔类型的 EOPL 具有重要价值。