Plenty of novel characteristics have been observed during inner-cavity and external cavity tuning in the orthogonally
polarized lasers which has attracted the interest of many researchers and been applied as sensors to measure angles,
displacements, wave plates' retardation, etc, and are often more accurate and affordable than currently available
interferometers or inductance transducers. However, effective theory models to explain the orthogonally polarized lasers'
characteristics are still hitherto unknown. In this paper, the inner-cavity and external cavity intensity tuning characters of
orthogonally polarized lasers with different parameters are studied, respectively. First, we discuss the semi-classical
theory model of orthogonally polarized laser based on the vectorial extension of Lamb's theory, and are compared with
the experimental results for tuning inner-cavity. Then the thought of multiple-beam interference is introduced to extend
the theory model to solve the problem of multiple feedback effects which appear as the external cavity is tuned in the
orthogonally polarized lasers and the experimental results agree well with theoretical analysis.