Intensity noise in long-wavelength superluminescent sources

Noise in broadband 1.3- mu m superluminescent diodes (SLDs) is investigated experimentally, using a balanced detector arrangement to determine the excess noise factor as a function of photodetector current. Measurements were made in both the low-frequency 1/f, regime (<500 kHz) and the high-frequency quantum noise spectral region. The data at higher frequencies are in agreement with predictions of the quantum amplifier model, with values of the spontaneous emission coupling factors ranging from 1.2 to 1.9. It is also found that noise for one polarization of the light is uncorrelated with the noise for the orthogonal polarization over the 0-1 MHz frequency range. This implies that the 1/f, noise is not related to carrier density (gain) fluctuations in the active region of the device. An integrated optic chip design to compensate for the excess intensity noise in fiber gyroscopes is proposed.<
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