This laser driver, ATLS4A214, is an electronic module that has all the valuable and important, but often difficult to achieve simultaneously, features simultaneously: wide input and output voltage range, high output current capability, high efficiency, low output noise, wide modulation bandwidth, and small size. The wide output voltage range, 0 ~ 15V, allows driving one or multiple serial laser diodes at the same time, for up to 4A well controlled current at high efficiency. The extremely low noise between DC ~ 3 kHz and low DC current drift make it ideal for driving diode pumped single mode laser diodes to achieve mode-hop-free and narrow optical wavelength drift, thus, long coherent length. Because of the high efficiency, the laser driver generates small amount of heat, thus, no heat sink is necessary for normal operation. The fully shielded case blocks all the incoming and outgoing EMIs (Electro-Magnet Interferences).