I just checked the simulation file of the KB example again. The pulse used in the example is fairly broadband (1.48-1.63 um) however the movie monitor scale factor is set to 0.1 (rather than default value of 1):
I hope this answered your question why you can the field profile in the KB example and how you can modify your movie monitor settings to obtain similar resutls.
Regarding the rest of the conversation:
As @aya_zaki and yourself mentioned, the movie monitor captures the whole pulse profile. So, while you have around 80% coupling at a specific wavelength, a big portion of the pulse is not coupled. Thus, you need to modify monitor scale to capture this week fields.
FDTD accounts for both material loss and radiation loss. Material loss is included in material properties and radiation loss is calculated during the simulation. FDTD propagates the light in time domain by solving Maxwell’s eqautions and demonstrated exact behaviour of light field.
I am not recommending using dipole sources. First, since your light is routed with a waveguide before coupling to the ring cavity, you need to use mode source. Second, dipole source also emit a pulse which will have a bandwidth.
If you want to study the coupled field at a specific wavelength, a good approach would be to use time monitors. You can see how the light field evolves in time and by Fourier transforming of the data, you can obtain the frequency domain data. Alternatively, you can visualize spectrum from time monitor.
Please let me know if you have further questions and I am happy to help.