Optical data storage based on magnetic circular dichroism

An alternative to differential detection in optical data storage is magnetic circular dichroism (MCD) detection. The MCD system has increased light efficiency when compared to the commonly used differential detection method. Also, the signal amplitude for MCD detection can be twice as large as for differential detection when an s‐p phase difference of 90° is introduced in the medium. Modeling results show that a thin‐film device can introduce the necessary s−p phase difference. Our signal‐to‐noise analysis indicates that the MCD system rejects polarization noise. Experimental results on coupon samples verify that the signal from MCD detection can be twice as large as from differential detection.