Effect of pulse asymmetry and nonlinear chirp on the accuracy of ultrafast pulsed laser interferometry.

Ultrafast pulsed laser interferometry (PLI) can measure picometer displacements at sub-nanosecond time scales, such as acoustic waves and vibrations in microstructures. In this Letter, the effects of pulse characteristics on the accuracy of PLI are investigated through measurements and modeling. The results show that the effective wavelength of PLI, λ, varies significantly as a function of overlap between the interfering pulses due to pulse asymmetry and nonlinear chirp.

Ultrahigh-finesse, low-mode-volume Fabry-Perot microcavity.

Ultralow-loss concave micromirrors with radius of curvature below 60 microm were fabricated by laser ablation and reflective coatings. A 10-microm-long microcavity with a mode volume of 40 microm(3) was set up with two such mirrors, and the cavity linewidth was measured both spectrally and temporally. The smallest linewidth obtained was 96 MHz, corresponding to a quality factor of 3.

Fabry-Perot metrology for displacements up to 50 mm.

A system designed to apply Fabry-Perot interferometry to the measurement of displacements is described. Two adjacent modes of a Fabry-Perot cavity are probed, and both the absolute optical frequencies and their difference are used to determine displacements via changes in cavity length. Light is coupled to the cavity via an optical fiber, making the system ideal for remote sensing applications.

United time-frequency spectroscopy for dynamics and global structure.

Ultrashort laser pulses have thus far been used in two distinct modes. In the time domain, the pulses have allowed probing and manipulation of dynamics on a subpicosecond time scale. More recently, phase stabilization has produced optical frequency combs with absolute frequency reference across a broad bandwidth.