The　paper　reports　that　the　lasing　wavelength　of　the　LD　changes　markedly　with　the　width　of　the　active　region.　The　lasing　wavelengths　of　the　LDs　emitting　at　960　nm,　which　have　the　same　epitaxial　growth　and　different　width　of　active　region,　are　investigated.　It　is　found　that　the　lasing　wavelength　of　the　device　is　becoming　short　as　the　stripe　width　is　getting　narrow.　Further　analysis　shows　that　it　is　caused　by　the　enhancement　of　the　threshold　current　density　and　threshold　carrier　density　in　terms　of　optical-gain　spectrum　of　GaAs　material,　and　that　is　the　result　of　narrowing　the　width　of　the　active　region.　Therefore,　the　lasing　wavelength　can　be　easily　modified　by　changing　the　stripe　width　of　LDs　in　practice.