Semiconductor laser and atomic oscillator

An atomic oscillator comprising:

• a semiconductor laser;
• an atom cell irradiated with light emitted from the semiconductor laser and containing alkali metal atoms;
• and
• a light receiving element that detects intensity of light transmitted through the atom cell and outputs a detection signal, wherein
• the semiconductor laser includes
• a first mirror layer,
• a second mirror layer,
• an active layer disposed between the first mirror layer and the second mirror layer,
• a current confinement layer disposed between the first mirror layer and the second mirror layer,
• a first region provided continuously with the first mirror layer and including a plurality of first oxidized layers, and
• a second region provided continuously with the second mirror layer and including a plurality of second oxidized layers,
• the first mirror layer, the second mirror layer, the active layer, the current confinement layer, the first region, and the second region constitute a laminated body,
• in a plan view, the laminated body includes
• a first part including the first region and the second region,
• a second part including the first region and the second region, and
• a third part disposed between the first part and the second part and resonating light generated in the active layer,
• the third part includes
• a fourth part including the first region and the second region and having a first groove,
• a fifth part including the first region and the second region and having a second groove, and
• a sixth part disposed between the fourth part and the fifth part and sandwiched between the first part and the second part, in a plan view.