I'm currently researching the intermodal distance of transverse and axial modes in optical cavities. But the equation defining the longitudinal separation contains the +- sign, does this imply that both those positions there are longitudinal modes?
Δν_transverse=c/(2∙L) [cos^(-1)(±√g_1g_2)/π]$Δν_{transverse}=\frac{c}{(2L)} \left[ \frac{cos^{-1}(\pm \sqrt{g_1g_2})}{π} \right]$
Furthermore, do the higher-order transverse modes of say; axial mode 1, overlap with the positions of higher order axial modes?
