Patent ID: 6445722
Filing Date: 2002-09-03
Classification: H01S

Abstract:
A laser diode which outputs single-transverse-mode light comprising:a multi-mode interference light waveguide region, amplifying transverse-mode light oscillating within said laser diode, said multi-mode interference light waveguide region having a length L and a width W1, the length L corresponding to the width W1 according to: L=(34&it;N)&it;LÏ€LÏ€=4&it;Nr&it;We23&it;Î»0We=W1+(Î»0Ï€)&it;(NcNr)2&it;Ïƒ&it;(Nr2-Nc2)-12a first single-transverse-mode light waveguide region connected to a first end portion of said multi-mode interference light waveguide region; and a second single-transverse-mode light waveguide connected to a second end portion of said multi-mode interference light waveguide region, said second end portion being opposite to said first end portion, wherein said multi-mode interference light waveguide region is wider than said first single-transverse mode waveguide region, and wider than said second single-transverse mode waveguide region, wherein said multi-mode interference light waveguide region operates as a 1Ã—N light waveguide, wherein N is a number of single-transverse light waveguide regions connected to said second end portion of said multi-mode interference light waveguide region, We is an effective width of said multi-mode interference light waveguide region, L&pgr; is a beat length of two lowest order modes, &lgr;0 is a wavelength of said single-transverse-mode light, Nc is a refractive index of a cladding portion of said multi-mode interference light waveguide region, Nr is a refractive index of a waveguide portion of said multi-mode interference light waveguide region, &sgr;=0 at a TE mode, and &sgr;=1 at a TM mode, and wherein single-transverse-mode light entering said multi-mode interference light waveguide from said first single-transverse-mode light waveguide region couples to said second single-transverse-mode light waveguide region.