This paper introduces a novel tunable external-cavity diode laser based on the grating light valve (GLV) technology, which has the advantages of high speed, high reliability, low cost and compactness. A theoretical model is present on this tunable laser and the configuration parameters are calculated to illustrate the practical signifiance of the laser.
A novel optical element, Dual-Cylindrical Prism, designed to generate and homogenize a laser beam line at an arbitrary working distance, is presented. The element with entrance surface consisting of two cylindrical shaped concave surfaces, and exit surface a single cylindrical concave, splits and overlaps the laser beam along fast axis and collimates the beam along slow axis, redistributing the diode laser output beam to a line with uniform intensity distribution and flexible working distance. The technique to design such a device is provided, and the computer-aided simulation results demonstrate the uniformity of the laser line and also the feasibility of such a device.
A theoretical model is presented to calculate the fiber coupling efficiency and alignment tolerances for the case of a 980nm 100μm broad-area diode laser directly coupled to a 100μm round-shaped cylindrical lensed multimode fiber. Both radius and wedge angle of the round-shaped cylindrical lens are optimized for maximum coupling efficiency. It is found that with proper design, a coupling efficiency of up to 98% may be obtained theoretically. The alignment tolerances for all three directions (vertical, horizontal, and axial offsets) are also calculated. It is found that the vertical offset (X-offset) tolerance is the most critical one among three, but is still acceptable (~2μm) for low-cost practical packaging. It is also found that the distance between the diode and the fiber, and the lens shape on the fiber can be further varied to improve this tolerance.