This paper describes on optical transmission system for a Time Compression Multiplexing (TCM) High Definition TV (HDTV) signal with a bandwidth of 20 MHz. Negative feedback is being employed to improve some of the shortcomings of the laser diode. In this paper the stability of the negative feedback circuit and its effect on reducing harmonic distortion and noise in the laser diode are examined. A laser diode module used in this experiment consists of a TJS-LD operating at a wavelength of 0.89 µm and a photo diode. In the final system, a method that superimposes high frequency pulses is employed for reducing modal noise. The signal-to-noise ratio (SNR) of the optical sender is achieved at 49 dB and harmonic distortion at about 44 dB, where the optical output level is 6.0 dBm and modulation depth is 0.5.