Light-emitting device including semiconductor laser element encapsulated by base and cover with two lead terminals penetrating through lateral wall of base

A light-emitting device comprising:

• a semiconductor laser element;
• a base having a bottom portion supporting the semiconductor laser element and a lateral wall surrounding the semiconductor laser element with the lateral wall being bonded to the bottom portion, the lateral wall including a light-transmitting portion configured to transmit a laser beam emitted from the semiconductor laser element;
• a cover, the cover and the base together defining an encapsulation space in which the semiconductor laser element is encapsulated;
• two lead terminals penetrating through the lateral wall of the base, one end of each of the lead terminals being located inside the encapsulation space;
• a submount arranged between the semiconductor laser element and the base, the submount having an upper surface and a lower surface with the upper surface of the submount supporting the semiconductor laser element;
• and
• a metal film provided on the lower surface of the submount,
• wherein the bottom portion of the base has an upper surface defining a recessed portion located between the two lead terminals as viewed from above,
• the recessed portion has a flat bottom surface over which the semiconductor laser element is placed
• the metal film and the bottom surface of the recessed portion are bonded to each other with a bonding material,
• a thickness of the metal film is greater than a depth of the recessed portion,
• in a separation direction in which the two lead terminals are separated as viewed from above, a width of the metal film is equal to or smaller than a width of the recessed portion, and
• in the separation direction, a width of the submount is greater than a width of the recessed portion and is smaller than a dimension of a gap between the two lead terminals.