| 摘要 |
<p>An optical clock (100) comprises a laser oscillator (102) and modulating means (106, 108, 110, 112, 114 116, 118, 112) arranged to cooperate with the laser oscillator to produce a series of phase-modulated optical pulses. The optical clock further comprises an optical fibre (128) arranged to provide compression of the optical pulses, and may also comprise a step-recovery diode (130) arranged to pulse-pick pulses output from the fibre to produce a series of optical clock pulses, depending on the mode of operation of the modulating means. Phase-modulation is carried out a frequency which provides sufficient linewidth broadening to inhibit stimulated Brillouin scattering within the optical fibre. An optical clock of the invention provides a robust and reliable alternative to clocks based on modelocked lasers, and may be assembled from inexpensive, commonly-available components. The repetition rate of a clock of the invention may easily be adjusted by electronic means. Unlike many modelocked lasers, a clock of the invention does not require precise optical alignment.</p> |
