In this study, the nonlinear optical (NLO) response of alkali metal atoms (Li, Na & K) and their corresponding superalkalis (Li3O, Na3O & K3O) doped six membered cyclic thiophene (6CT) has been explored. Optimized geometry of complexes [email protected], [email protected], [email protected], Li3[email protected], Na3[email protected] and K3[email protected] depict that the superalkalis and alkali metals interact through the active cavity of 6CT. Interaction energies reveal that superalkalis has high interaction with 6CT than alkali. Nonlinear optical (NLO) response of reported complexes are estimated via both static and dynamic hyperpolarizabilities which are further rationalized by HOMO-LUMO gap, natural bond orbital (NBO) charge transfer, dipole moment, polarizabilities and βvec. Remarkably high NLO response is computed for Na3[email protected] complex among all complexes. The static hyperpolarizability of Na3[email protected] complex is 5×104 au along with the highest βvec value (2.5×104 au). High charge transfer (1.53 e–) and small EH-L gap (2.96 eV) is responsible for such a large NLO responses. For dynamic NLO response, electro-optic Pockel’s effect (EOPE) and second-harmonic generation (SHG) are explored. Very large quadratic nonlinear optical response (3.8×10-12) is observed for Na3[email protected] complex. Moreover, the absorption spectrum of Na3[email protected] complex illustrates ultra-high transparency in ultraviolet and visible region unlike other counterparts.