LASER DIODE HAVING STRUCTURE FOR IMPROVING NOISE-CHARACTERISTICS OF OPTICAL EXTERNAL FEEDBACK

摘要

A laser diode having a structure for improving noise-characteristics of an optical external feedback is provided to reduce optical interference by improving an arrangement structure of a laser diode chip and a lens. A laser diode includes a laser diode chip(104) mounted on a stem(101), a lens cap(106) coupled with the stem, and a lens(107) installed on the lens cap in order to focus laser beams emitted from the laser diode chip. A gap between the laser diode chip and the lens is set to lower coupling efficiency as much as 10 to 20 percent of a maximum value when a transmittance of a laser beam to a center of the lens is 97 to 98 percent. In addition, the gap between the laser diode chip and the lens is set to lower the coupling efficiency above 20 percent and more of the maximum value when the transmittance of the laser beam to the center of the lens is less than 97 percent.