Semiconductor laser

A semiconductor laser comprising:

• an optical resonator that has a first compound semiconductor layer containing an n-type impurity, a second compound semiconductor layer containing a p-type impurity, and a light-emitting layer provided between the first compound semiconductor layer and the second compound semiconductor layer;
• a first electrode electrically connected to the first compound semiconductor layer;
• a second electrode electrically connected to the second compound semiconductor layer;
• an insulation layer provided to cover a part of the second compound semiconductor layer;
• and
• a pulse injection means connected to the first electrode and the second electrode,
• wherein the light-emitting layer has a multiple quantum well structure in which at least five well layers and at least five barrier layers are alternately stacked,
• the optical resonator has a multi-section structure separated into at least one gain region and at least one absorption region along an oscillation direction,
• the pulse injection means is configured to apply a pulse current for a duration of less than 1 ns to the first electrode and the second electrode,
• an electrode area of the second electrode is set so that the excitation energy is injected for a sub-nanosecond duration into the optical resonator when the pulse current is applied to the first electrode and the second electrode,
• a stray capacitance around the insulation layer is set so that the excitation energy is injected for a sub-nanosecond duration into the optical resonator when the pulse current is applied to the first electrode and the second electrode, and
• the semiconductor laser generates optical pulses having a pulse width shorter than 2.5 times a photon lifetime in the optical resonator.