I just did a quick Google Scholar search and came up with...

Campbell, M. T. H. R. G. D. M., et al. "Fabrication of photonic crystals for the visible spectrum by holographic lithography." Nature 404.6773 (2000): 53-56.

Subramania, G., et al. "Optical photonic crystals fabricated from colloidal systems." Applied Physics Letters 74.26 (1999): 3933-3935.

Iwayama, Yumie, et al. "Optically tunable gelled photonic crystal covering almost the entire visible light wavelength region." Langmuir 19.4 (2003): 977-980.

Matsuu, Masaaki, et al. "Formation of periodically ordered zinc oxide nanopillars in aqueous solution: An approach to photonic crystals at visible wavelengths." Advanced Materials 18.12 (2006): 1617-1621.

Arsenault, André C., et al. "Photonic-crystal full-colour displays." Nature Photonics 1.8 (2007): 468-472.

Crozier, K. B., et al. "Air-bridged photonic crystal slabs at visible and near-infrared wavelengths." Physical Review B 73.11 (2006): 115126.

This should get you started.  Some of these may not be purely 2D.

Check this as well, 

Bill C et al, Green Light Emission in Silicon through Slow Light Enhanced Third-Harmonic Generation in Photonic Crystal Waveguides, .

https://www.researchgate.net/publication/31938469_Green_Light_Emission_in_Silicon_through_Slow_Light_Enhanced_Third-Harmonic_Generation_in_Photonic_Crystal_Waveguides

This group is extensively working on Nonlinear effects in Photonic crystal . 

Using diamond as waveguide is quite new , you may not find much literature related to it. You may have to follow standard design in lumerical for GaAs or Si  by changing their material library . 

Article Green Light Emission in Silicon through Slow Light Enhanced ...

All application of photonic crystals are  used the infra red light 

where the visible light suffer from the material loss through the silicon and the range of infra red light which lies between 1550 and 1650 nm has lowest losses