These LDs have been optimized for operation at low output power levels of up to 10 mW using EXALOS-patented design concepts. recently, significant improvements in lowering the lasing threshold currents for blue sky and green LDs have been achieved by EXALOS with lasing doorway currents around 5 massachusetts for blue sky LDs and approximately 15 milliampere for green LDs, thereby further reducing the electrical power dissipation of these light modules [ 9 ] .
All LDs show a closely gaussian far-field ( FF ) distribution along the horizontal focus with alike FWHM far field angles of 9-10° for all three colors, demonstrating lateral single-mode operation. In the vertical direction, the FF distributions are typically a snatch different for GaAs-based red LDs and GaN-based blue and fleeceable LDs, with FWHM farfield angles of 27° for crimson, 20° for green and 22° for gloomy. While the horizontal FF distribution is chiefly governed by the etch depth and the width of the ridge waveguide, the upright FF distribution is determined by the epitaxial layer structure, namely by the deflective index contrast of the waveguide and, frankincense, by the mode confinement. normally, GaN based epitaxial structures feature a lower index contrast and hence a smaller restriction agent, which translates into a larger upright near discipline and, consequently, into a narrower far field distribution in upright commission .
The collimation efficiency with the micro-optical lenses is closely 100 % when the LDs are driven above the lasing threshold as hardly any remainder ad-lib discharge or substrate escape modes are emitted from the LD chips once they are operating in the stimulated-emission manner. The high-performance insulator edge filters have low insertion losses of less than 2 %, which means that the gradient efficiency values of the RGB LD faculty is very similar to the one of the free-space LD chips.

Fig. 4 and Fig. 5 show the diameters for the RGB radio beam as a affair of distance from the module, either at the 50 % relative volume level ( Fig. 4 ) or at the 1/e2 or 13.5 % relative intensity flush ( Fig. 5 ). The first RGB LD prototype modules were built for a mention distance of d=50 millimeter, which means that the glow shapes and glow overlap were optimized at this distance from the RGB module.

furthermore, the parallel air of the green LD was used as a character beam as it has the strongest contribution to the ocular perception of a white-light air. This beam has, at a distance d=50 millimeter, about perfect circularity or oblateness of 0.97 as the 1/e2 balance beam diameters in the horizontal direction ( 250 μm ) and in the vertical direction ( 245 μm ) are closely identical. The parallel gloomy glow has 1/e2 beam diameters of 425 μm and 325 μm, respectively, and therefore achieves a circularity higher than 80 %. Given the similar horizontal and vertical far-field angles of the green and blasphemous LD, a better match to the beam parameters of the fleeceable glow should be accomplishable for the blue beam, though .
For the bolshevik beam, the 1/e2 horizontal beam diameter is 440 μm, which is alike to what has been achieved for the blue glow. however, in the erect direction, the 1/e2 beam diameter is 650 μm, which is importantly larger than the vertical beam size of the aristocratic and park beam. This is by and large related to the larger vertical deviation of the bolshevik LD chip, as mentioned earlier, which is something that EXALOS will correct shortly with a modern generation of red LD ( and SLED ) chips that
have exchangeable vertical divergence values as the blue devices .

Leave a Reply

Your email address will not be published.