The frequency-doubled Nd:YAG laser: A potential transmitter in an optical communication system

An internally frequency-doubled, mode-locked Nd: YAG laser has been used to produce an output pulse train of sub-nanosecond 5320Å pulses. The laser operates in the TEM
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transverse mode and produces an average harmonic output of approximately one-half watt. The interaction between intra-cavity harmonic generation and mode locking affects the output pulse train in several aspects including pulse repetition frequency and pulse length. These effects and the long-term stability of the laser are discussed. This laser is particularly suitable for use as the transmitter of a pulse-code-modulation optical communication system. Although the 5320Å YAG laser has previously been considered for this application, crystal damage and output pulse stretching, have limited its usefulness. This paper describes a laser which overcomes these limitations.