Semiconductor laser element with excellent high-temperature characteristic and capable of being readily mounted on an optical circuit board

A semiconductor laser element, comprising:

• a semiconductor block including a laser beam emitting portion and having:
• a first end surface;
• a second end surface opposite to said first end surface;
• a principal surface contiguous to said first and said second end surfaces;
• an internal end surface obtained by forming a U-shaped groove from said principal surface into said semiconductor block, said internal end surface providing a laser beam emitting surface for an optical resonator formed between said internal end surface and said second end surface;
• and
• a plurality of active layers interposed between cladding layers and having a multiple quantum well structure;
• wherein said active layers comprise:
• at least five wells which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.35 .mu.m and 1.45 .mu.m and
• barriers which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.05 .mu.m and 1.20 .mu.m,
• wherein said second end surface is remote from said first end surface by a predetermined distance of substantially at least 250 .mu.m, and
• wherein said internal end surface is remote from said second end surface by a predetermined distance not longer than 150 .mu.m.

A semiconductor laser element, comprising:

• a semiconductor block including a laser beam emitting portion and having:
• a first end surface,
• a second end surface opposite to said first end surface;
• a principal surface contiguous to said first and said second end surfaces;
• an internal end surface obtained by forming a rectangular groove from said principal surface into said semiconductor block, said internal surface providing a laser beam emitting surface for an optical resonator formed between said internal end surface and said second end surface, and
• a plurality of active layers interposed between cladding layers and having a multiple quantum well structure;
• wherein said active layers comprise:
• at least five wells which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.35 .mu.m and 1.45 .mu.m and
• barriers which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.05 .mu.m and 1.20 .mu.m,
• wherein said second end surface is remote from said first end surface by a predetermined distance of substantially at least 250 .mu.m, and
• wherein said internal end surface is remote from said second end surface by a predetermined distance not longer than 150 .mu.m.

A semiconductor laser device comprising:

• an optical fiber which has an end portion;
• a circuit board having a board surface;
• a semiconductor block including a laser beam emitting portion and which is mounted on said board surface and which has:
• a first end surface;
• a second end surface opposite to said first end surface;
• a principal surface contiguous to said first and said second end surfaces;
• an internal end surface obtained by forming a U-shaped groove from said principal surface into said semiconductor block, said internal surface providing a laser beam emitting surface for an optical resonator formed between said internal end surface and said second end surface;
• and
• a plurality of active layers interposed between cladding layers and having a multiple quantum well structure;
• wherein said active layers comprise:
• at least five wells which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.35 .mu.m and 1.45 .mu.m and
• barriers which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.05 .mu.m and 1.20 .mu.m,
• wherein said second end surface is remote from said first end surface by a predetermined distance of substantially at least 250 .mu.m,
• wherein said internal end surface is remote from said second end surface by a predetermined distance not longer than 150 .mu.m, and
• wherein said end portion of said optical fiber is fitted into said U-shaped groove to be optically coupled to said laser beam emitting surface.

A semiconductor laser device comprising;

• a circuit board having a board surface;
• an optical waveguide which has an end portion and which is formed on said board surface;
• a semiconductor block including a laser beam emitting portion and which is mounted on said board surface and which has:
• a first end surface;
• a second end surface opposite to said first end surface;
• a principal surface contiguous to said first and said second end surfaces;
• an internal end surface obtained by forming a rectangular groove from said principal surface into said semiconductor block, said internal surface providing a laser beam emitting surface for an optical resonator formed between said internal end surface and said second end surface;
• and
• a plurality of active layers interposed between cladding layers and having a multiple quantum well structure;
• wherein said active layers comprise:
• at least five wells which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.35 .mu.m and 1.45 .mu.m and
• barriers which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.05 .mu.m and 1.20 .mu.m,
• wherein said second end surface is remote from said first end surface by a predetermined distance of substantially at least 250 .mu.m,
• wherein said internal end surface is remote from said second end surface by a predetermined distance not longer than 150 .mu.m, and
• wherein said end portion of said optical waveguide is fitted into said rectangular groove to be optically connected to said laser beam emitting surface.

A semiconductor laser element, comprising:

• a semiconductor block which has a length not shorter than 250 micrometers and which includes a laser beam emitting portion, said semiconductor block comprising:
• a first end surface;
• a second end surface opposite to said first end surface and remote from said first end surface by a predetermined distance of substantially at least 250 .mu.m;
• a principal surface contiguous to said first and said second end surfaces;
• an internal end surface obtained by forming a U-shaped groove from said principal surface into said semiconductor block, said internal end surface providing a laser beam emitting surface for an optical resonator formed between said internal end surface and said second end surface and having a length not longer than 150 micrometers;
• a plurality of coating layers which are coated on said second end surface to provide a reflectivity not lower than 90%;
• and
• active layers interposed between cladding layers and having a multiple quantum well structure;
• wherein said active layers comprise:
• wells which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.35 .mu.m and 1.45 .mu.m and
• barriers which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.05 .mu.m and 1.20 .mu.m, and
• wherein said semiconductor laser element is arranged to produce a light output greater than 5 mW in response to an input current not larger than 30 mA at 85.degree. C.

A semiconductor laser element, comprising:

• a semiconductor block which has a length not shorter than 250 micrometers and which includes a laser beam emitting portion, said semiconductor block comprising:
• a first end surface;
• a second end surface opposite to said first end surface and remote from said first end surface by a predetermined distance of substantially at least 250 .mu.m;
• a principal surface contiguous to said first and said second end surfaces;
• an internal end surface obtained by forming a rectangularly shaped groove from said principal surface into said semiconductor block, said internal end surface providing a laser beam emitting surface for an optical resonator formed between said internal end surface and said second end surface and having a length not longer than 150 micrometers;
• a plurality of coating layers which are coated on said second end surface to provide a reflectivity not lower than 90%;
• and
• active layers interposed between cladding layers and having a multiple quantum well structure;
• wherein said active layers comprise:
• wells which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.35 .mu.m and 1.45 .mu.m and
• barriers which are made of InGaAsP lattice-matched with InP and which have a composition defined by a bandgap corresponding to a wavelength between 1.05 .mu.m and 1.20 .mu.m, and
• wherein said semiconductor laser element is arranged to produce a light output greater than 5 mW in response to an input current not larger than 30 mA at 85.degree. C.