A slider configured for heat-assisted magnetic recording has an upper surface, an opposing air bearing surface (ABS), and a body defined between the upper surface and the ABS. The slider comprises a write pole and a near-field transducer (NFT) at or near the ABS. An optical waveguide is configured to receive light from a laser source and comprises a first cladding layer, a second cladding layer, and a core between the first and second cladding layers. The core has a width, a length, and a longitudinal axis oriented along the length of the core. A bolometer is situated within the body of the slider at a location that receives at least some of the light communicated along the waveguide used during a writing operation. The bolometer is spaced apart from the core and comprises a longitudinal axis that is oriented substantially parallel to the longitudinal axis of the core.