Wavelength locker

#1. Field of the Invention

#The present invention is related to devices used to monitor and control coherent radiation sources. More specifically, it relates to devices that measure and maintain output wavelengths of coherent radiation sources.

#2. Description of Related Art

#These and other objects and advantages of the invention will become more apparent and more readily appreciated from the following detailed description of the presently preferred exemplary embodiments of the invention, taken in conjunction with the accompanying drawings, of which:

#FIGS. 1A and 1B are schematic illustrations of a semiconductor etalon according to one embodiment of the present invention;

#FIG. 2 illustrates an embodiment of the present invention as incorporated as part of a system to monitor and maintain the output wavelength of a coherent radiation source;

#In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular optical and electrical circuits, circuit components, techniques, etc. in order to facilitate a thorough understanding of the present invention. However, the invention may be practiced in other embodiments that depart from these specific details.

#FIGS. 1A (plan view) and 1B (side view) illustrate a semiconductor etalon 110 according to an embodiment of the present invention. A semiconductor plate, or portion thereof, is etched or otherwise processed to provide semiconductor etalon 110 having a plurality of resonance regions 112a, 112b, 112c and 112d with different thicknesses. Each of said plurality of resonance regions 112a–112d has an arbitrarily shaped cross sectional area which is substantially parallel to either face of the semiconductor plate. In the embodiment illustrated in FIG. 1A, the plurality of resonance regions 112a–112d comprise a square pattern of four contiguous squares, but the semiconductor etalon 110 according to the present invention is not in any way constrained to only the number and/or geometrical arrangement of the plurality of areas 112a–112d shown.

#In one embodiment of the present invention, having the geometry illustrated in FIGS. 1A and 1B, each of said plurality of resonance regions 112a–112d is processed so as to have thicknesses which differ in steps of one eighth of a wavelength (in the semiconductor), for a wavelength that is preferably near the middle of the range of wavelengths to be measured. In this embodiment, the thickest of the plurality of resonance regions 112a–112d is diagonally opposed to the thinnest of said resonance regions, but said plurality of resonance regions 112a–112d may be arbitrarily arranged according to thickness.