Disclosed is a working end of a surgical instrument for delivering heat energy to tissue. The working end includes paired first and second jaw members movable between open and closed positions, with each jaw member defining a jaw body and jaw end-effecter for engaging and heating tissue. At least one jaw member contains an electromagnetic-energy emitter coupled to an electromagnetic-energy source, the electromagnetic-energy emitter is located within the jaw end-effecter, and the jaw end-effecter includes an insert made of an electromagnetic-energy absorbing material.