Semiconductor light emitting device and photocoupler

A semiconductor light emitting device comprising:

• a light emitting layer having a first surface and a second surface provided on an opposite side of the first surface, the light emitting layer being capable of emitting emission light having a peak wavelength in a wavelength range of 740 nm or more and 830 nm or less, and the light emitting layer being made of one of AlxGa1-xAs (0≦x<0.45) and InxGa1-xAs (0≦x≦1);
• a first layer of a first conductivity type provided on a side of the first surface of the light emitting layer and having a light extraction surface provided on opposite side from the light emitting layer;
• a second layer of a second conductivity type provided on a side of the second surface of the light emitting layer;
• and
• a distributed Bragg reflector layer provided on a side of the second layer opposite to the light emitting layer and having the second conductivity type, a third layer made of one of InxAl1-xP (0≦x≦1) and AlyGa1-yAs (0≦y≦1) and a fourth layer made of AlzGa1-zAs (0≦z≦1) being alternately stacked in the distributed Bragg reflector layer, and the distributed Bragg reflector layer being capable of reflecting the emission light toward the light extraction surface,
• the third and fourth layers each having a bandgap wavelength shorter than the peak wavelength.

A photocoupler comprising:

• a semiconductor light emitting device including:
• a light emitting layer having a first surface and a second surface provided on an opposite side of the first surface, the light emitting layer being capable of emitting emission light having a peak wavelength in a wavelength range of 740 nm or more and 830 nm or less;
• a first layer of a first conductivity type provided on a side of the first surface of the light emitting layer and having a light extraction surface provided on opposite side from the light emitting layer;
• a second layer of a second conductivity type provided on a side of the second surface of the light emitting layer;
• and
• a distributed Bragg reflector layer provided on a side of the second layer opposite to the light emitting layer and having the second conductivity type, a third layer and a fourth layer with a higher refractive index than the third layer being alternately stacked in the distributed Bragg reflector layer, and the distributed Bragg reflector layer being capable of reflecting the emission light toward the light extraction surface,
• the third and fourth layers each having a bandgap wavelength shorter than the peak wavelength;
• a semiconductor light receiving device capable of receiving the emission light from the semiconductor light emitting device and converting the emission light to an electrical signal;
• an input lead connected to the semiconductor light emitting device;
• an output lead connected to the light receiving device and electrically insulated from the input lead;
• and
• a support supporting the input lead and the output lead and being capable of internally housing the semiconductor light emitting device and the semiconductor light receiving device.