A laser source is provided by the present invention, comprising a laser diode and has an active region with asymmetric distributed Bragg reflectors (DBRs) at either end to reflect light within the cavity, and an outcoupling grating in the center of the device, which couples light out of the cavity. One DBR is long and shallow, with a narrow-band reflective spectrum. The other DBR is short and deep, with a wide-band reflective spectrum. The lasing wavelength is determined by the reflective spectrum overlap of the two DBRs. Since the shallow DBR is highly reflective to only one Fabry Perot wavelength, and the deep DBR is highly reflective to a wide band of Fabry-Perot wavelengths, it is the reflective spectrum of the shallow DBR that determines the lasing wavelength.