| 摘要 |
The modulation measuring sytem uses an optical waveguide (1) within an integrated optical or fibre optic circuit with a cooperating phase-shifting element (5) at a variable distance (d) from a section (1') of this waveguide (1), for adjusting the effective refractive index and hence the phase of the optical waves travelling along the waveguide section (1'). The relative spacing (d) of the phase-shifting element (5) from the waveguide section is sufficiently small to obtain an exponential attenuation function, without significant loss of power of the propagated waves. The spacing (d) is varied as a function of time to obtain the required modulation, or the effective variations in the refractive index and the phase of the propagated waves are used to measure the spacing variations.
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