Ultra-compact and high-performance photonic crystal ring resonator–based demux may achieve low crosstalk, high Q-factor, and effective multichannel operation in the C-band. In this study, we propose a novel 6-channel dense wavelength division demultiplexer based on photonic crystal hexagonal ring resonators is designed and analyzed. To obtain the linearity in the intensity of demux, a novel technique of tuning holes is incorporated. By adjusting the radii of resonator holes and monitor holes – collectively known as special holes, the resonating wavelengths are precisely adjusted. Six asymmetrical hexagonal ring resonators are used in the suggested demux to accomplish effective channel separation. The Finite-Difference Time-Domain Method approach is used to examine the device performance, while the Plane Wave Expansion Method is employed to derive the photonic bandgap structure. For short-haul optical communication systems, the design maintains a channel spacing of 0.8 nm in accordance with ITU-T specifications. The suggested demux achieves crosstalk levels between −17.23 dB and −23.97 dB and a quality factor of 12,875 spanning a wavelength range of 1,544 nm–1,550 nm in the C-band. Compact design and improved selectivity for Dense Wavelength Division Multiplexing applications are achieved by using an asymmetrical hexagonal resonator with optimal hole tuning.