The medium noise reduction by intensity dividing readout in the magneto-optical memories

Medium noises in a magneto-optical memory are analytically discussed on an experimental basis. We propose the intensity dividing readout (IDR) method for the reduction of medium noise. The IDR method has the following merits: (1) Noises caused by intensity fluctuation can be cancelled out, (2) the carrier-to-noise ratio (C/N) becomes insensitive to an analyzer angle (φ) and reaches a maximum when φ is 45°, (3) in addition, the current gain (M) of the avalanche photo diode (APD) can be lowered, because it receives a maximum light intensity when φ=45°. Consequently, IDR method does not need any fine adjustment of sensitivity, input power and φ of detectors.