Problem to be solved: to provide a surface emitting laser having a small wavelength dependency of optical output intensity or threshold current value.A bottom reflecting mirror, an active layer, a gap portion, and an upper reflector, which are in this order and are capable of varying the wavelength of light emitted by varying the distance between said lower reflector and said upper reflector, wherein said surface emitting laser is located under said lower Having a driving portion for displacing one of the part reflecting mirror and the upper reflector in the direction of the optical axis of the light to be emitted, the wavelength. Lambda.. sub.g whose maximum gain at the time of laser oscillation of the active layer is maximized, the central wavelength. Lambda.. sub.0 of the light being emitted, and the reflection on the side where the light is emittedA surface emitting laser characterized in that the relationship of the wavelength. Lambda.. sub.r at which the reflectivity of the mirror is maximized is made to satisfy. Lambda.. sub.r <. Lambda.. sub.0 < \u03bb g or. Lambda. G <. Lambda.. sub.0 <. Lambda.. sub.r.Diagram【課題】 光出力強度または閾値電流値の波長依存性の小さい面発光レーザを提供すること。【解決手段】 下部反射鏡と、活性層と、空隙部と、上部反射鏡と、をこの順に有し、前記下部反射鏡、前記上部反射鏡との間の距離を変化させることによって出射する光の波長を可変とする面発光レーザであって、前記下部反射鏡と前記上部反射鏡のいずれか一方を前記出射する光の光軸方向に変位させる駆動部を有し、前記活性層のレーザ発振時の利得が最大となる波長λg、前記出射する光の中心波長λ0、前記光が出射される側の反射鏡の反射率が最大となる波長λrの関係が、λr<λ0<λgもしくはλg<λ0<λrを満たすように構成されていることを特徴とする面発光レーザ。【選択図】 図1
