Method for forming coating film on facet of semiconductor optical device

A method for forming a coating film on a facet of a semiconductor optical device, the method comprising the steps of:

• preparing an epitaxial wafer by forming a multilayer semiconductor structure including an active layer on a main surface of a substrate;
• forming a plurality of stripe electrodes and a plurality of bonding pads on the multilayer semiconductor structure of the epitaxial wafer, the stripe electrodes extending longitudinally in a first direction and being arranged in a second direction that is perpendicular to the first direction, the bonding pads being respectively electrically connected to the stripe electrodes;
• forming a projection portion on the multilayer semiconductor structure of the epitaxial wafer to have a height measured from the main surface of the substrate that is greater than a height of the stripe electrodes;
• forming a plurality of laser diode bars by cutting the epitaxial wafer in the second direction;
• arranging the laser diode bars on a support surface such that a side surface of at least one laser diode bar is oriented in a normal direction of the support surface, and disposing spacers between the laser diode bars;
• and
• forming a coating film on the side surface of the at least one laser diode bar, wherein,
• the at least one laser diode bar has at least one projection portion, and
• the at least one projection portion has a height measured from the main surface of the substrate that is less than a height of the bonding pads measured from the main surface.

A method for forming a coating film on a facet of a semiconductor optical device, the method comprising the steps of:

• preparing an epitaxial wafer by forming a multilayer semiconductor structure including an active layer on a main surface of a substrate;
• forming a plurality of stripe electrodes and a plurality of bonding pads on the multilayer semiconductor structure of the epitaxial wafer, the stripe electrodes extending longitudinally in a first direction and being arranged in a second direction that is perpendicular to the first direction, the bonding pads being respectively electrically connected to the stripe electrodes;
• forming a projection portion on the multilayer semiconductor structure of the epitaxial wafer to have a height measured from the main surface of the substrate that is greater than a height of the stripe electrodes;
• forming a groove extending in the second direction in a back surface of the substrate;
• forming a plurality of laser diode bars by cutting the epitaxial wafer into segments in the second direction along the groove;
• arranging the laser diode bars on a support surface such that a side surface of at least one laser diode bar is oriented in a normal direction of the support surface, and disposing spacers between the laser diode bars;
• and
• forming a coating film on the side surface of the at least one laser diode bar, wherein,
• the at least one laser diode bar has at least one projection portion, and
• the at least one projection portion is formed a distance from the side surface of the at least one laser diode bar that is shorter than a distance between the side surface and the bonding pad, and that is equal to a distance between the side surface of the at least one laser diode bar and a sidewall of the groove.