Pulse Lasers can deliver a significant amount of damage in a single hit. Unlike other Lasers that fire continuously when triggered, a pulse laser fires intermittently in an on/off fashion. Compared to the other two laser types it emits the least waste heat, draws the least distributor energy and is also cheapest, at the cost of DPS/Damage.
Commonly supplied in 2 hardpoints when you buy any new ship, pulse lasers are available as fixed, gimballed and turreted types.
As with all lasers they are thermic damage so offer increased damage when stripped shields. Out of all lasers they have the best armour piercing capability (although its still low) making them a good choice for ships with limited hardpoints.
When fitting Pulse Lasers you will often be using them as a low-power slot-filler. They are very effective against shields, but can also hit police/friendly targets so should still be used with caution. Scramble spectrum effect or any non-stacking event is best employed in a Class 1 slot. Whenever your build is short of power or distributor capacity, pulse lasers are great to fill it out. Overcharge has minimal effect on efficiency which means that with G5 engineering Pulse Lasers can almost match Efficient Beams in DPS while outperforming hugely in terms of distributor draw and thermals. If employed in a Huge hardpoint, Phasing Sequence is excellent to wear down shield tank builds (often seen on the Cutter or FDL).