a seed laser configured to produce optical seed pulses at one or more operating wavelengths between approximately 1400 nm and 2050 nm, wherein the seed laser comprises:

a plurality of laser diodes; and

an optical multiplexer configured to combine light produced by the plurality of laser diodes into a single optical fiber;

a first fiber-optic amplifier configured to amplify the optical seed pulses with a first gain to produce a first amplifier output that comprises amplified seed pulses and amplified spontaneous emission (ASE);

a first optical filter configured to remove from the first-amplifier output at least a portion of the ASE by transmitting light at the one or more operating wavelengths and attenuating light at other wavelengths by at least 20 dB;

a second fiber-optic amplifier configured to receive the amplified seed pulses from the first optical filter and to amplify them with a second gain to produce output pulses having a pulse repetition frequency less than or equal to 100 MHz, a pulse duration less than or equal to 20 nanoseconds, a duty cycle less than or equal to 1%, a pulse energy greater than or equal to 10 nanojoules, a peak power greater than or equal to 1 watt, and an average power less than or equal to 50 watts, the ASE comprising less than or equal to 25% of the average power; and

a plurality of sensor heads to direct at least a portion of the output pulses into a plurality of fields of view and to detect reflected or scattered light therefrom.