Coupled quantum well tunable laser

The present invention is the use of coupled quantum wells (122, 126) in the active region of a semiconductor laser (30) to modulate the frequency and amplitude of the light output (50) of the laser (30). In a particular embodiment of the present invention the coupled quantum wells (122, 126) are contained in a graded index (115, 130) of refraction semiconductor double heterostructure laser (30). The active region (120) of this tunable laser (30) consists of two quantum wells (126, 122) having a width of approximately 5 nm or less which are separated by a barrier layer (124) having a width of approximately 2 nm or less. The quantum well material is intrinsic GaAs and the barrier layer is AlxGa1-xAs wherein x=.23. The active region (120) is surrounded by the double heterostructure in which one side is doped p-type and the second side is doped n-type. The resulting laser (30) is a p-i-n type structure. A reverse bias with respect to the flat band voltage of the p-i-n structure is applied across the p-i-n structure which modulates both the frequency and the intensity of the laser output (50). The tunable laser (30) is pumped with a variety of conventional means, including both electrical and optical (40) pumping. The modulation of the wavelength is approximately linear over a 1.5 volt operating range. A tunable laser (30), such as the present invention, having an output wavelength modulated by an electric field is useful in the field of optical communications and computing.