Coherent light generators – Particular beam control device – Optical output stabilization
Patent
1991-10-08
1992-12-15
Epps, Georgia Y.
Coherent light generators
Particular beam control device
Optical output stabilization
372 19, 372 99, H01S 313
Patent
active
051723832
ABSTRACT:
Accurate mode partition data from a laser are collected simply and rapidly in accordance with the principles of the invention wherein the laser output is directed to a filter which separates a central longitudinal mode from the side modes. The filter operates to present all side modes in a predetermined wavelength range simultaneously and continuously at the output of the filter. By subsequently comparing the intensity or power in the side modes delivered to the filter output with a predetermined threshold, it is possible to determine the frequency of occurrence and magnitude of mode partition events for side modes in the predetermined wavelength range. In one exemplary embodiment, the filter is realized by the combination of a Fabry-Perot etalon, whose longitudinal axis is angled with respect to the longitudinal axis (propagation axis) of the laser output beam directed onto the filter, together with an external reflector which is parallel to the Fabry-Perot etalon to permit multi-passing of the beam between the Fabry-Perot etalon and the reflector. The beam is reflected by the Fabry-Perot etalon so that after two or more passes within the filter only the side modes are output by the filter. In this arrangement, the filter acts as a notch filter having a wide passband and having an output for the side modes which is separate from an output for the main mode.
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Magill Peter D.
Reichmann Kenneth C.
AT&T Bell Laboratories
Epps Georgia Y.
Ranieri G. C.
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