Photonics

Photonics is where electromagnetism meets quantum mechanics: instead of treating light as just a classical wave, you learn to quantize the field, count photons, and track how they exchange energy with atomic systems through absorption, spontaneous emission, and stimulated emission — the last being what makes lasers possible. The work is heavily computational, with weekly homeworks and quizzes asking you to calculate transition rates, gain coefficients, saturation behavior, and steady-state populations in pumped media using Saleh & Teich as the reference. Sitting on top of your EM and quantum background, it turns abstract field theory into the working physics behind real devices — laser diodes, LEDs, photodetectors, electro-optic modulators — and is the natural entry point if you want to do optoelectronics, integrated photonics, or quantum optics later.