“…Our main strategy is to use the linearization technique of Isakov and others [28,29,30,31,32] in dealing with nonlinear equations to decompose the inverse problem to the semilinear radiative transport equation ( 1) into an inverse coefficient problem for the linear transport equation where we reconstruct σ a and σ s by the result of Bal-Jollivet-Jungon [6], and an inverse source problem for the linear transport equation where we reconstruct the two-photon absorption coefficient σ b . This is the same type of strategy that have been successfully employed to solve many inverse problems for nonlinear PDEs recently; see for instance [4,11,13,14,15,18,20,25,26,33,35,36,38,39,40,41,43,44,45,46,47,50,58,61,62,63] and reference therein.…”