Pulse Repetition Rate
The pulse repetition rate (or pulse repetition frequency) frep of a regular train of pulses is defined as the number of emitted pulses per second, or the inverse temporal pulse spacing.
Depending on the technique of pulse generation, typical pulse repetition rates can be in different parameter regions:
- Typical mode-locked solid-state lasers emit with pulse repetition rates between 50 MHz and a few gigahertz, but in extreme cases < 10 MHz or > 100 GHz are possible.
- Q switching of solid-state lasers typically allows repetition rates from below 1 Hz to the order of 100 kHz.
- Gain switching of semiconductor lasers can provide repetition rates from below 1 Hz to many megahertz.
- Attosecond pulse trains of finite length can be generated via high harmonic generation with repetition rates of hundreds of terahertz.
If a pulse train is regular and the pulses are mutually coherent, the optical spectrum of the pulse train is a frequency comb, where the spacing of the lines is determined by the pulse repetition rate.
The deviation from perfect periodicity of the optical power is called timing jitter.
See also: pulse generation, pulses, frequency combs, timing jitter
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