A new type of optical switch is constructed of graded-index rod lenses. It is operated mechanically by small electromagnets. This switch is compatible with practical multimode-fiber communication systems. It has many outstanding features, such as low insertion loss (1.3-1.4 dB), low crosstalk (<-60 dB), high stability (< 0.1 dB), low driving power (˜5V dc, 100 mA), high durability (>2 X 106 times), and small size (40 × 50 × 25 mm3). © 1979, Optical Society of America.