Trw Limited

William W Simmons

Michael Jansen

Jane J Yang

Jaroslava Z Wilcox

Dan Botez

Luke J Mawst

Arnold H Silver

Hagop Injeyan

Lee O Heflinger

Randall J St Pierre

Moshe Sergant

Gary L Peterson

Apparatus and a related method for generating a second harmonic frequency optical output from a fundamental frequency input beam, without significant birefringence. The apparatus includes two Type II doubler crystals of equal length arranged with their corresponding axes parallel to each other, and a polarization rotator positioned between the doubler crystals, to rotate the polarization angle of a residual fundamental frequency component of an output beam from one of the crystals by 90.degree. or an odd multiple of 90.degree.. Random birefringence introduced into one of the doubler crystals is virtually canceled in the other, and the assembly of the two crystals and the polarization rotator may be angularly adjusted as needed for phase matching or tuning, without detracting from the birefringence compensation capability. The invention is also disclosed in the context of a phase conjugated master oscillator power amplifier (PC MOPA) system.

Birefringence-compensated alignment-insensitive frequency doubler

A semiconductor laser array with features providing good beam quality at high powers, first by employing a laterally unguided diffraction region in which light from a set of waveguides is re-imaged in accordance with the Talbot effect and two arrays of waveguides may be used to provide a spatial filtering effect to select a desired array mode. This provides a laser array with increased power per unit solid angle, and with additional advantages of ability to scale the device up to larger arrays, ability to control the electrical excitation of the device for better optimization, and improved modal discrimination. A second aspect of the invention is the use of a resonance condition in an antiguide array, to produce a uniform near-field intensity pattern and improved coupling and device coherence. This resonance structure may be combined with the Talbot-effect structure to suppress the out-of-phase mode, or the out-of-phase mode may be suppressed by other means, such as by introducing interelement radiation losses or absorption losses in the antiguide array.

Semiconductor laser array having high power and high beam quality

An ion milling method is disclosed that provides a manufacturing technique for mass producing microscopic surface features using a wide variety of media that includes semiconductors, metals, and glasses. In the preferred embodiment, vertical and 45 degree mirrors are formed simultaneously in semiconductor laser diodes in order to produce monolithic two dimensional arrays of surface emitting lasers. Standard double heterostructure semiconductor laser diodes are first grown on a wafer using metalorganic chemical vapor deposition techniques. An ion milling gun is oriented at a particular angle from the longitudinal axis of the active layer of the laser and emits a stream of atomic particles toward the lasers producing a generally two sided cut or notch that extends downward from the top surface of the semiconductor laser and traverses the active layer. The two sides of the cut consist of a vertical face that is perpendicular to the active layer and an inclined mirror surface that connects to the bottom of the vertical face and the slopes back upward to the top of the laser. Although the preferred utilization of this invention is the production of high power semiconductor laser arrays and subsequent wafer scale integration, the ion milling technique may be employed to construct a wide variety of micro-miniature radiation interfaces, reflectors, transmitters, or absorbers. Virtually any surface that requires a specifically determined configuration of uniform topography of atomic proportions may be produced.

Ion milling method

An array of semiconductor lasers formed in a single substrate and having parallel waveguides that terminate in a wide diffraction region fabricated with the array structure. The diffraction region has a curved reflective surface selected to achieve a desired degree of coupling among the elements of the array, and to enhance and stabilize a preferred lateral mode of oscillation.

Semiconductor laser array with nonplanar diffraction region

A diffraction-coupled semiconductor laser array, and a related method for its operation, the array structure having a diffraction section that is electrically controllable independently of a waveguide section having multiple laser channels. Above a critical level of injected gain in the diffraction region, and with appropriate selection of channel and diffraction region dimensions, stable operation in the in-phase supermode results, with adjacent lasers operating in phase and a single-lobed far-field distribution pattern being produced. Below the critical level of injected gain, the out-of-phase supermode or multimode operation is favored and the narrow single peak of the far-field pattern is no longer present. This mode switching can be used to rapidly modulate operation of the array without directly switching it on and off.

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Rancho Palos Verdes, CA, United States of America

William W Simmons