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US 6,445,722 B2Granted
Single-transverse-mode laser diode with multi-mode waveguide region and manufacturing method of the same
AssigneeNEC Corporation
InventorKiichi Hamamoto
Life of this patent
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Abstract
A laser diode with a single-transverse-mode output having a laser cavity comprising both single-mode and multi-mode waveguide portions, and a method of manufacturing such a laser diode are disclosed. There are a pair of single transverse waveguide regions at opposite ends of a multi-mode waveguide. The multi-mode waveguide is a 1×1-multi-mode interference waveguide, with a wider width than the single-mode portions. Use of the multi-mode region improves the power output, threshold current density, and overall efficiency in comparison to a similarly constructed laser diode in which the entire laser cavity is single-mode.
Claims6
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 = ( 3 4 N ) L π L π = 4 N r W e 2 3 λ 0 W e = W 1 + ( λ 0 π ) ( N c N r ) 2 σ ( N r 2 - N c 2 ) - 1 2
- a 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 1×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, Lπ is a beat length of two lowest order modes, λ0 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, σ=0 at a TE mode, and σ=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.
6 more elements
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 = ( 3 N ) L π L π = 4 N r W e 2 3 λ 0 W e = W 1 + ( λ 0 π ) ( N c N r ) 2 σ ( N r 2 - N c 2 ) - 1 2
- a 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 N×N light waveguide,
- wherein N is a number of single-transverse light waveguide regions connected per end portion at the first and second end portions of said multi-mode interference light waveguide region, We is an effective width of said multi-mode interference light waveguide region, L90 is a beat length of two lowest order modes, λo 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, σ=0 at a TE mode, and σ=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.
6 more elements
Dependencies are inferred from the claim text.