recombination around the junction and within the diffusion length of the electrons in the p-side leads to spontaneous photon emission.
potential energy is charge* potential = q v
extraction efficiency = (loss from the exit cavity end) / (total loss)
at sufficiently high diode currents corresponding to high optical power, the operation becomes single mode.
宴会与宴席的含义是不同的，宴席含义广，宴会含义窄。
麦克斯韦方程1式代表电场的高斯定律：电场可以是有源场；电力线必须从正电荷出发终止于负电荷。
partially reflected waves at the corrugations can only constitute a reflected wave when the wavelength satisfies the bragg condition.
麦克斯韦方程的微分形式在真空中和介质中形式有所不同。
power conversion efficiency=optical output power / electric input power
the forward voltage across a pn junction increases by dv, which leads to further minority carrier injection and a larger forward current, which is increases by di. additional minority carrier charge dq is injected into the n-side. the increase dq in charge stored in the n-side with dv appears as if there is a capacitance across the diode.