  We show that by using a perturbed photonic Dirac-cone, one can realize
ultra-narrow and finite Q-factor peak in the wavevector space, with both the
peak value and the width separately tunable. We also discuss a lower bound in
the minimal viable width given a peak Q-value while maintaining sufficient Q
differentiation among modes. The strong angular and frequency Q-selection finds
applications in optical devices where strong angle- and frequency-selection is
needed.
