Examples described herein relate to an optical resonating device. The optical resonating device includes a primary waveguide, a microring resonator, and a microring resonator photodiode. The primary waveguide allows a passage of an optical signal. The microring resonator is formed adjacent to the primary waveguide to couple therein a portion of the optical signal passing through the primary waveguide. Furthermore, the microring resonator photodiode is formed adjacent to the microring resonator to measure an intensity of the portion of the optical signal coupled into the microring resonator.