Looking for a 3.3V IR sensor
Vishay offers a series of fully integrated IR proximity sensors such as the VCNL4000 that operate from 2.5 Volts through 3.6 Volts. This particular part has an I2C interface. Other parts in the family have different interface options. 

For something with a simpler pulse-width interface, consider Vishay TSSP4P38 and its smaller counterparts. These require a separate IR LED emitting at 38 KHz.

The mechanism used is different between the Sharp and Vishay devices. The Vishay part uses daylight-filtered reflected IR intensity to determine proximity, while the Sharp part uses angular displacement of IR signal reflected from the target. Thus, results may be different depending on the actual deployment scenario.