Method for generating gigahertz bursts of pulses and laser apparatus thereof

A method for generating bursts of laser pulses, which comprises forming delayed parts and undelayed parts of input pulses of a primary pulse train, wherein said delayed and undelayed parts of input pulses form an output train of bursts of pulses,

• wherein
• a time delay (T2) of the delayed part of any input pulse with respect to the undelayed part of that input pulse is longer than M*T1, where T1 is a time period between adjacent input pulses, M=2, 3,
• the output train of bursts is composed of bursts of pulses wherein M adjacent bursts have an identical number of pulses, and said identical number of pulses in each next set of M adjacent bursts is increased by 1;
• an intra-burst pulse separation (T3) of the formed bursts is equal to T3=T2-M*T1 and corresponds to an ultra-high pulse repetition rate higher than 100 MHz.

A laser apparatus for implementing a method for generating bursts of laser pulses from a primary pulse train,

• comprising
• a seed source,
• a burst synthesizer and
• a power amplifier,
• wherein
• the burst synthesizer is composed of an active fiber loop and a fiber coupler with a first and a second input ports and a first and a second output ports, wherein the active fiber loop characterized by an optical length (Lopt) connects the first output port of the fiber coupler with its first input port and introduces a time delay (T2) of a part of the input pulse with respect to another part of said input pulse;
• and said active fiber loop contains:
• an isolator:
• a wavelength division multiplexer;
• a laser diode;
• a segment of a doped optical fiber;
• an optical switch controlled by a drive signal (D2);
• a segment of an undoped optical fiber;
• wherein the segment of the doped optical fiber is used for pulse amplification, while the optical switch is used to block or attenuate parts of pulses propagating in the active fiber loop.