Fischer’s research is in Electro-Optics/Photonics. It includes Nonlinear-Optics, Photorefractive and Phase-Conjugate Optics, Pulse-Optics, Fiber-Optics, Fiber-Optic-Communication and Many-Body Photonics (phase-transitions and critical phenomena in lasers), thermalization of photons in fibers, classical condensation effects in lasers, and quantum-based Bose-Einstein Condensation (BEC) of photons in fibers. The works were done with his students and colleagues. He authored or co-authored about 300 journal and conference papers and holds nine patents in the field of photonics.