A 1.88 μm Ba(NO3)2-based stimulated Raman scattering (SRS) laser pumped by a potassium-titanyl-phosphate-based optical parametric oscillator (OPO) laser is presented. Under the pumping energy of a 130 mJ 1064 nm Q-switched Nd:YAG laser, a 40 mJ 1.57 μm laser is achieved; the maximum output energy of