Laser diode module

Abstract

A laser diode module is provided which is capable of suppressing reduction in the efficiency of laser beam coupling with an optical fiber even in the case where a warp is caused in the mounting surface of a thermo electrical cooler on which a laser diode chip is mounted. A laser diode module has a heat sink and optical coupling portion mounted directly or indirectly on a mounting surface of a thermo electrical cooler. A laser diode chip and the optical coupling portion are located on the same side of the mounting surface along the emitting direction of a laser beam emitted from the laser diode chip, with respect to a first center line (L cpp ) intersecting perpendicularly with a tangential plane tangent to the mounting surface of the thermo electrical cooler at the center thereof and/or a second center line passing through the center of the mounting surface of the thermo electrical cooler and perpendicular to both the first center line and an axis representative of the emitting direction of the laser beam.

What is claimed is:  
     
         1 . A laser diode module comprising: 
 a laser diode chip;    a thermo electrical cooler for controlling temperature of said laser diode chip to a predetermined temperature;    a heat sink arranged between said laser diode chip and said thermo electrical cooler for transferring heat from said laser diode chip; and    an optical fiber for guiding a laser beam emitted from said laser diode chip to outside via optical coupling means, all of said laser diode chip, said thermo electrical cooler, said heat sink and said optical fiber being housed in a package,    characterized in that said heat sink and said optical coupling means are mounted directly or indirectly on a mounting surface of said thermo electrical cooler, and    said laser diode chip and said optical coupling means are located on an identical side of the mounting surface along an emitting direction of the laser beam, with respect to a first center line intersecting perpendicularly with a tangential plane tangent to the mounting surface of said thermo electrical cooler at a center thereof and/or a second center line passing through the center of the mounting surface of said thermo electrical cooler and perpendicular to both the first center line and an axis representative of the emitting direction of the laser beam emitted from said laser diode chip.    
     
     
         2 . A laser diode module, comprising: 
 a laser diode chip;    a thermo electrical cooler for controlling temperature of said laser diode chip to a predetermined temperature;    a heat sink arranged between said laser diode chip and said thermo electrical cooler for transferring heat from said laser diode chip; and    an optical fiber for guiding a laser beam emitted from said laser diode chip to outside via optical coupling means, all of said laser diode chip, said thermo electrical cooler, said heat sink and said optical fiber being housed in a package,    characterized in that said heat sink and said optical coupling means are mounted directly or indirectly on a mounting surface of said thermo electrical cooler, and    said laser diode chip and said optical coupling means are arranged in a manner such that, where an axis representative of an emitting direction of the laser beam emitted from said laser diode chip is projected onto the mounting surface of said thermo electrical cooler with use of a bundle of light rays intersecting perpendicularly with a tangential plane tangent to the mounting surface of said thermo electrical cooler at a location directly under said laser diode chip, thereby obtaining a projected line image, and also where said laser diode chip and said optical coupling means are projected onto the mounting surface with use of the bundle of light rays, thereby obtaining respective projected images, the projected images of said laser diode chip and said optical coupling means are located on the projected line image of the axis and on an identical side of the mounting surface with respect to a middle point of a line segment connecting two points at which the projected line image intersects with a contour line representative of a contour of the mounting surface.    
     
     
         3 . The laser diode module according to    claim 1   , wherein said laser diode chip is located closer to the center of the mounting surface of said thermo electrical cooler than said optical coupling means.  
     
     
         4 . The laser diode module according to    claim 2   , wherein said laser diode chip is located closer to the center of the mounting surface of said thermo electrical cooler than said optical coupling means.  
     
     
         5 . The laser diode module according to    claim 1   , wherein said optical coupling means is mounted on said thermo electrical cooler with a base interposed therebetween, and a portion of the base on which said optical coupling means is mounted partly extends beyond the mounting surface.  
     
     
         6 . The laser diode module according to    claim 2   , wherein said optical coupling means is mounted on said thermo electrical cooler with a base interposed therebetween, and a portion of the base on which said optical coupling means is mounted partly extends beyond the mounting surface.  
     
     
         7 . The laser diode module according to    claim 3   , wherein said optical coupling means is mounted on said thermo electrical cooler with a base interposed therebetween, and a portion of the base on which said optical coupling means is mounted partly extends beyond the mounting surface.  
     
     
         8 . The laser diode module according to    claim 1   , wherein said optical coupling means is formed at an end of said optical fiber and includes a portion with an end face which is formed like a lens and on which the laser beam emitted from said laser diode chip falls.  
     
     
         9 . The laser diode module according to    claim 2   , wherein said optical coupling means is formed at an end of said optical fiber and includes a portion with an end face which is formed like a lens and on which the laser beam emitted from said laser diode chip falls.  
     
     
         10 . The laser diode module according to    claim 3   , wherein said optical coupling means is formed at an end of said optical fiber and includes a portion with an end face which is formed like a lens and on which the laser beam emitted from said laser diode chip falls.  
     
     
         11 . The laser diode module according to    claim 4   , wherein said optical coupling means is formed at an end of said optical fiber and includes a portion with an end face which is formed like a lens and on which the laser beam emitted from said laser diode chip falls.