Provided are a high-speed superluminescent diode, a method of manufacturing the same, and a wavelength-tunable external cavity laser including the same. The primary winding is connectable to an AC voltage supply and circuitry on the secondary side is arranged to provide a DC output voltage for the electrical device. The second film thickness is less than the first film thickness and the surface free energy of the second surface free energy region is made higher than the surface free energy of the first surface free energy region by applying a predetermined amount of energy on the second surface free energy region. The voice authentication system compares the collected voice samples to stored voice samples to determine the identity of the first party. Also, the present invention reduces the amount of signal loss between the photocell output and an amplifier due to loading at the input stage of the amplifier. The system automatically generates a default noise index from a received set of scan parameter values that specifies a desired tube current of an X-ray source to use during the scanning of a patient.