Slow light in ellipse-hole photonic crystal line-defect waveguide with high normalized delay bandwidth product

Abstract

In this paper, a novel flatband slow light device with low group velocity dispersion (GVD) is presented in an ellipse-hole photonic crystal (PC) line-defect waveguide. Utilizing dispersion engineering in the proposed structure, normalized delay-bandwidth product (NDBP) under a constant group index criterion is significantly improved. A step-by-step optimization process is done on the adjacent rows to the waveguide, which are filled by silica. For optimum case a high NDBP of 0.461 with a group index of 41.86 and a bandwidth of 17.06 nm is obtained by three-dimensional plane-wave expansion method. To the best of our knowledge, this NDBP is one of the highest values in PC waveguides reported to date, in which the group index value is relatively high. The numerical results show that GVD is negligible over a broad wavelength range. Also, optical pulse propagation through the waveguide is performed based on the finite-difference time-domain method. The results indicate that the shape of output pulse experiences a broadening of 2.1% compared with the incoming pulse after traveling a distance of 30a.

Tunable hexagonal boron nitride topological optical delay line in the visible region

“…1(c), which is suitable for most applications [12] . The group velocity dispersion (GVD) parameter β 2 , which affects the distortion of short optical pulse is expressed by the second-order derivative of the dispersion relation [47] :…”

“…For the performance of these types of waveguides filled with liquid crystals at different voltages, see Supplementary Material, Section 6. In addition, we discuss the time domain analysis of the ODL based on the straight waveguide [47] , and compare the performance of the proposed slow-light waveguide with a conventional PC slow-light waveguide in the Supplementary Material, Section 3. This proves that this result is the best among any slowlight waveguides in the visible region, to the best of our knowledge, which makes it suitable for most applications.…”

Slow-light effect in symmetry-reduced non-defect photonic crystals

“…Apart from these approaches, researchers have continued to perform studies that explore basic photonic crystal waveguide (PCW) structures. PCWs subject to various different modifications were studied to enhance slow wave performance of propagating light pulses (Moghaddam & Fleury, 2019;Hocini et al 2018;Schulz et al 2017;Han et al 2015;Varmazyari et al 2014;Khodamohammadi et al 2015).…”

Wideband slab photonic crystal waveguides for slow light using differential optofluidic infiltration

“…The other techniques are based on nearly zero dispersion, in which the PCW geometry is changed. The most appropriate parameters to be changed are the width of the waveguide [22], the hole size [23], the position of holes in the first two rows (usually with different displacement in the first row instead of the second one) [24][25][26][27], and usage of the annular holes [28]. Nevertheless, fabrication of such structures requires nanometer-scale precision that can limit the applications of PCWs.…”