9B7 - Direct frequency modulation of a semiconductor laser by ultrasonic waves

A discussion is given of frequency modulation of a semiconductor laser using ultrasonic waves. The principle used is the modulation of the dielectric constant of the material by the sound waves. This modulates the laser output due to the refractive index dependence of the mode frequencies. It is shown that a very high index of modulation can be achieved. Experimental results are reviewed for a gallium arsenide diode laser. Limitations of this technique and possible devices are considered.