Abstract: A semiconductor tunable laser system includes a tunable Fabry-Perot cavity and a cavity length modulator, which controls an optical length of the cavity at least over a distance corresponding to the spacings between the longitudinal modes of the laser cavity. Thus, the tunable Fabry-Perot cavity allows the laser cavity to have gain at the desired wavelength of operation while the cavity length modulator tunes the cavity length such that a longitudinal cavity mode exists at the desired wavelength of operation. Also, in one embodiment, a wavelength locker system is further provides that has a differential wavelength filter, e.g., stepped etalon, and a multi-element detector, e.g., a quad-detector. The controller then modulators the Fabry-Perot cavity to control the wavelength in response to the signal received from the multi-element detector.

Abstract: An apparatus and method for stabilizing the transverse mode of laser oscillation in a vertical cavity semiconductor laser and a microchip laser are disclosed. A preferred embodiment includes a quantum-well region formed over a semiconductor substrate. A first reflective surface is formed over the quantum-well region, and a second reflective surface is formed over the substrate, opposite the first reflective surface, forming a laser cavity. The quantum-well region is optically pumped, producing laser oscillation. The absorbed pump power causes a thermal lensing effect within the semiconductor material, stabilizing the transverse spatial mode of the laser cavity. The radius of curvature of the thermal lens is a function of absorbed pump power. Maximum power conversion efficiency is achieved if the pump power is controlled such that the diameter of the oscillating mode matches the diameter of the pump beam. The invention has applications in optical communication and laser printing.

Abstract: An apparatus and method for producing laser radiation from a vertical cavity semiconductor laser are disclosed. A preferred embodiment includes a quantum-well region formed over a semiconductor substrate. A first reflective surface is formed over the quantum-well region, and a second reflective surface is formed over the substrate, opposite the first reflective surface, forming a laser cavity. The quantum-well region is optically pumped, producing laser oscillation. The absorbed pump power causes a thermal lensing effect within the semiconductor material, stabilizing the transverse spatial mode of the laser cavity. The invention has applications in optical communication and laser printing.

Abstract: A tunable waveguide grating includes a plurality of N waveguides which define N optically transmissive pathways. A plurality of (N-1) electrodes are arranged in the pathways such that the kth pathway contains (k-1) electrodes, where 0<k<N. As a result of this arrangement, an optical signal propagating through the kth pathway will experience a phase shift provided by each of the (k-1) electrodes arranged in that pathway. Consequently, in contrast to prior tunable optical gratings, each electrode may contribute a phase shift to the portions of the signal propagating through several waveguides and hence as the number of waveguides increases no individual electrode is required to produce relatively large phase shifts.

Abstract: The present invention relates to a new tunable filter which, when used as an intracavity mode selecting filter in a semiconductor laser structure, provides a large tuning range. The disclosed filter is, in one embodiment, a two branch asymmetric Y-branch tunable filter where the ends of the two branches terminate at a common plane. In another embodiment, the invention is realized by using a cascade of two or more Y-branches to place several asymmetrical Y-branch filters in parallel.

Abstract: We describe an interferometric, channel-dropping, optical filter that includes a pair of planar waveguides. The two waveguides are spaced apart by a distance which is periodically varied along the longitudinal axis of the filter in order to effect a periodic optical coupling between them. There are at least three coupling locations, each associated with a coupling constant. The two waveguides have nominally equal effective refractive indices. In preferred embodiments of the invention, the coupling constants decrease symmetrically from the center of the filter toward the ends.