Abstract

Carrier sweep-out as a fast recovery mechanism has previously been investigated in a range of multiple quantum well (MQW) saturable absorbers (SA), for example [1]. We describe a PIN SA incorporating InGaAsP quaternary wells and barriers, lattice matched to InP which can be used as a reflective saturable absorber at wavelengths in the erbium gain window and present the first measurements of carrier sweep-out in such a device The MQW incorporates 60 wells to increase the contrast ratio under saturation and due to the quaternary structure presents low barriers to free carriers in both the conduction band and valence band wells to facilitate sweep-out. A distributed Bragg reflector (DBR) designed for operation at 1545nm is positioned below the MQW region allowing reflective operation The DBR and MQW are grown on an n* substrate in a single MOVPE step Devices are fabricated as 100μm diameter mesa structures with anti-reflection coating to suppress Fabry- Perot effects (Figure 1).

© 2000 IEEE