Alan E. Bell

Antireflection structures for optical recording

Thin-film antireflection structures find a natural application in high density optical video recording systems. We describe the design and optimization of two new antireflection structures which are suitable for use in conjunction with a wide variety of recording media, including both organic dyes and metals. Our experimental results show that by using these new designs it is possible to achieve improvements in both the recording sensitivity and the playback signal-to-noise ratio of the optical video disk.

Diode laser optical recording using trilayer structures

A new high-power diode laser and a more sensitive trilayer disk structure useful for FM video and digital data recording have been demonstrated. The diode laser is a constricted double-heterojunction large optical cavity (CDH-LOC) device capable of up to 100 mW output power in a single stable mode. By improving the thermal efficiency of the trilayer structure, the sensitivity is improved by a factor of two over previously reported trilayer structures. Digital signals with data rates up to 30 Mbits/s and storage capacity in excess of 3 \times 10^{10} bits are demonstrated using a plastic 12 in diameter disk rotating at 30 r/s while digital systems with data rates up to 60 Mbits/s and storage capacity in excess of 1011bits are shown to be feasible.

Reversible optical recording in trilayer structures

The reversible optical recording of FM video signals is reported. The recording medium is based upon the amorphous‐to‐crystalline phase transition of pure tellurium, incorporated into a trilayer antireflection structure. In excess of 50 record/erase cycles have been demonstrated, with no significant degradation in playback signal quality or erasability. The irreversible process of ablative pit formation (hole opening) has been inhibited by the use of a silicon dioxide capping layer.