A B737-700 First Officer's microphone switch stuck causing the aircraft to loose ATC communications. After squawking 7600 the crew proceeded to the airport and followed air traffic control's light signals.

Narrative

I was the Captain and pilot flying. Approximately 10 miles southeast of ABCDE at 6000 FT we experienced a stuck microphone with Approach Control. Subsequently we lost communications with Approach. Unable to resolve the situation; it apparently was a problem with the First Officer's toggle switch; and due to our close proximity to the airport; I elected to squawk 7600 and follow another carrier we had been previously told we were to follow to the runway. We appropriately configured the aircraft and landed uneventfully with appropriate light gun signals from the Tower for landing clearance. Light gun signals continued from Tower while we were on the ground clearing us to our gate. We continued our radio transmissions during this event in the blind not knowing if they were being received or not. We received no responses from ATC. I called Tower from the gate and told them what had happened with the First Officer's mic switch and Maintenance was already working the problem. They requested no call; it was a courtesy call by me. The aircraft was written up and released to Company Maintenance.