Maximum bandwidth of a composite achromatic quartz half-wave plate

To investigate the characteristics of the achromatic bandwidth of composite achromatic quartz half-wave plates (QHWPs), three kinds of multi-element achromatic QHWPs with central wavelengths at 1000-3000 nm and relative deviation of the maximum phase retardation (Δδ) of 1%-5% are discussed. Based on the particle swarm optimization algorithm, the maximum bandwidth of the composite achromatic QHWPs at room temperature is obtained. The results show that the achromatic bandwidth increases with Δδ. At the same Δδ, the achromatic bandwidth of four-element achromatic QHWPs is larger than that of two- and three-element achromatic QHWPs. The maximum achromatic bandwidth of four-element achromatic QHWPs can reach 2229 nm when Δδ is 5%. In addition, the temperature effect on bandwidth in the wavelength range of 300-1500 nm is analyzed, and the maximum bandwidth of temperature insensitive composite achromatic QHWPs is 840 nm. The results provide a great reference for designing achromatic wave plates with broad bandwidths.