The laser is a semiconductor diode with a p and an n region like the LED. Unlike LED, with reflecting mirrors on each end of the diode the laser has an optical cavity that contains the emitted photons. One of the reflecting mirrors is only partially reflective. Because of this mirror, some of the photons escape the optical cavity. For high-speed networking popular laser source is the vertical-cavity surface-emitter laser (VCSEL). This semiconductor diode is an ideal choice for the gigabit networking options and combines high bandwidth at a low cost. The optical alignment machine is of reasonable price.
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