In recent years, space laser communication technology has developed rapidly, distinguishing itself from traditional microwave communication by its compact size, lightweight design, low power consumption, high transmission rates, and superior resistance to interference. These advantages have made it a prominent area of research in the field of international space communication. Given the vast distances involved in satellite-to-satellite communication, maintaining a high-quality laser beam wavefront is crucial, which in turn places high demands on the optical system. Currently, wavefront error is the primary metric used to evaluate the design, manufacture, and alignment of the optical systems used in space laser communication terminals, without specifically considering individual aberrations. However, many scholars in the academic community have observed that different aberrations affect space laser communication in distinct ways. This study focuses on the impact of aberrations on laser communication, establishing a transmission model for space laser communication based on the far-field distribution of the complex amplitude of the optical wave. The study analyzes the effects of the cross-coupling of various aberrations on the received intensity and centroid shift, and proposes an optimal aberration tolerance allocation method for different wavefront errors. This research provides valuable insights for the development and optimization of optical systems with the goal of ensuring high-stability signal transmission in space laser communication.

This study utilized Zernike polynomials to model wavefront errors and performed optical field transmission simulations. First, a comprehensive optical field propagation model was developed, which covered the path from the transmitter to the focal plane of the receiver. An analysis demonstrated that aberrations at the transmitter could affect the centroid intensity at the focal plane of the receiver. Next, the interactions between aberrations were examined, identifying coupled aberrations among tilt, coma, defocus, and spherical aberration. Subsequently, based on the relationship between the Zernike polynomials and wavefront errors, coefficients were computed for individual aberrations under various root mean square (RMS) wavefront errors. Finally, the impact on the capture deviation and centroid intensity in the laser communication system was assessed using the derived coefficient allocation relationships, leading to the determination of optimal aberration allocation ratios for each component of the system.

Simulation analyses are conducted on the different terminals of the laser communication system. For the receiver terminal, considering the presence of cross-coupling aberrations, the impact of the aberration tolerance allocation on the received centroid intensity and capture deviation is studied. The presence of a spherical aberration and defocus at the receiver end is found to increase the received centroid intensity, with the optimal allocation ratio being 0.67 (Fig.10). It is observed that when the receiver end exhibits a combination of tilt and coma, the aberration distribution will have a compensatory effect on the capture deviation only when the total wavefront error exceeds a certain threshold (Fig. 6). For the transmission from the transmitter to the focal plane of the receiver, aberrations at the transmitter are found to have almost no impact on the received centroid shift but do affect the received focal plane intensity. Therefore, when the transmitter contains interacting aberrations, such as tilt and coma, and defocus and spherical aberration, tolerance allocation of these aberration combinations can effectively improve the capture centroid intensity (Fig.8), with fixed ratios of 0.82 and 0.43, respectively. Additionally, a universal validation of the results shows that the tolerance allocation method exhibits high stability (Figs. 7, 9, and 11).

This paper proposes a novel and effective tolerance allocation method for aberrations based on laser communication optical field transmission and aberration theory, which can significantly enhance the overall optical performance of laser communication systems. The impact of aberration tolerance allocation on laser communication performance includes its effects on the received centroid intensity and centroid position shift. Regarding centroid intensity, both the transmitter and receiver terminals exhibit negligible cross-coupling effects from aberrations when the wavefront error is small. However, when the wavefront error becomes large, certain specific combinations of aberrations can effectively improve the centroid intensity, even achieving a better overall performance compared to that with a smaller wavefront error. As for centroid position shift, because of the long-distance transmission, the wavefront error at the transmitter has no significant impact, and only the wavefront error at the receiver affects the performance. Similarly, when the wavefront error is large, specific combinations of aberrations can effectively mitigate the centroid shift phenomenon, leading to better alignment. The above conclusions can provide valuable guidance for the efficient development of optical systems for space laser communication to achieve superior communication performance at minimal cost, or offer detailed technical references for the active compensation of wavefront distortions, enhancing system stability and reliability.