Abstract: This specification discloses a VCSEL (Vertical Cavity Surface-Emitting Laser) device with single-mode output. This device is given by coating a layer of antireflection-coating (AR-coating) film on a normal VCSEL device with multiple transverse mode output and forming a light-emitting window on the AR-coating film. Since the AR-coating film can lower the reflectivity of the VCSEL device with multiple transverse mode output and the Bragg reflector at the bottom of the AR-coating film, it is easier to form single-mode laser light when the current flows through areas not covered by the AR-coating film, outputting a single-mode laser beam. Through the power-current character curve and the spectrum properties, one can find an optimal electrical current value for controlling single-mode light output.