Pulsed electrical operation of 1.5-μm vertical-cavity surface-emitting lasers
Vertical cavity surface emitting lasers operating in the 1.3- and 1.5-/spl mu/m wavelength ranges are highly attractive for telecommunications applications. However, they are far less well-developed than devices operating at shorter wavelengths. Pulsed electrically-injected lasing at 1.5 /spl mu/m, at temperatures up to 240 K, is demonstrated in a vertical-cavity surface-emitting laser with one epitaxial and one dielectric reflector. This is an encouraging result in the development of practical sources for optical fiber communications systems. >
This study compared ultrasonic and laser measurements of citrus canopy volume with manual measurement ::: methods. Fifteen trees with different canopy heights and volumes were used. Manual and ultrasonic measurements provided ::: dimensions for computing the canopy volume whereas laser measurements gave information that could be used to compute ::: a ‘laser canopy volume index.’ Ultrasonic and laser methods agreed with manual methods (R 2 > 0.85, RMSE < 2.15 m 3 ). Laser ::: showed better prediction of canopy volume than the ultrasonic system because of the higher resolution. Ultrasonic or laser ::: sensors can be used for automatic mapping and quantification of the canopy volumes of citrus trees.