Abstract

Cryogenic operation of semiconductor lasers offers the potential for greater bandwidth due to improved frequency modulation response,^1,2 lower threshold current, and higher power efficiency³ over that of room temperature operation. The 3- dB electrical modulation bandwidth can be determined from the relaxation oscillation frequency as located from the peak in the relative intensity noise (RIN) spectrum.⁴ In this report we show that the cryogenic RIN of a commercial 1.5 μm InGaAsP laser is significantly reduced below room temperature values over a major portion of a 22 GHz measurement bandwidth, yielding increased potential for ultrahigh speed modulation. Low RIN lasers are also useful for determining the optimum performance of advanced photodetectors, for measuring noise figure of optical fiber amplifiers, and as reference standards for the comparison and evaluation of RIN measurements.

© 1996 Optical Society of America