Mathematical models for the superimposed orbital angular momentum (OAM) mode of multiple Hankel-Bessel (HB) beams in anisotropic non-Kolmogorov turbulence are developed. The effects of anisotropic turbulence and source parameters on the mode detection spectrum of the superimposed OAM mode are analyzed. Anisotropic characteristics of the turbulence in the free atmosphere can enhance the performance of OAM-based communication. The HB beam is a good source for mitigating the turbulence effects due to its nondiffraction and self-focusing properties. Turbulence effects on the superimposed OAM mode can be effectively reduced by the appropriate allocation of OAM modes at the transmitter based on the reciprocal features of the mode cross talk.OCIS Light can carry both spin angular momentum (SAM) and orbital angular momentum (OAM), where SAM is associated with polarization and OAM is related to the spatial profile of the intensity and phase [1] . The SAM with two orthogonal modes is well known and widely exploited in present free-space optical (FSO) systems to double the channel capacity [2] . Recently, there has been a growing interest in utilizing advanced OAM modes of light to enhance the channel capacity and spectral efficiency in FSO links [3] . OAM-based FSO systems have been employed to demonstrate high-capacity information transmission with a link distance of ∼1 m at the lab scale [4] . OAM modes are inevitably sensitive to turbulence interference in the atmosphere because of their natural spatial structure [5] . The ability to transmit OAM modes over long-distance free space is crucial in order to take such lab-scale experiments into the real world [6] . Several investigations [5][6][7][8][9][10] have revealed that the effective range of the transmitted OAM modes with a small ratio of the mode cross talk in the atmosphere were restricted to a relatively narrow range because of turbulence effects. Turbulence-induced scintillation significantly caused the cross talk among OAM modes [7] , reduced information capacity [8] , and induced the spread of the OAM mode detection spectrum [9,10] . Superimposed OAM modes of multiple vortex beams possess more peculiar distribution structures and more controllable parameters for their potential applications in microparticle manipulation [11] and optical information encoding [12] compared with the conventional single-OAM mode. The superimposed OAM mode of multiple Laguerre-Gaussian (LG) beams have been studied in depth because of their simplicity of generation [12,13] . Classical information encoded by the superimposed OAM mode has recently started to be tested in real scenarios over a 3 km-long distance with significant turbulence, and showed that the phase of the superimposed OAM mode could be well conserved during the transmission in the turbulent atmosphere [12] . A low-density parity check-coded modulation architecture using coherent superimposed OAM mode for an optimal signal constellation was proposed in Ref. [13]. Recently, nondiffraction vortex beams [14][15][16][17] w...