Q2. What is the main advantage of using porous core PCF?
Using porous core PCF has a number of important advantages such as lower material absorption loss, lower dispersion, geometries such as pitch size, air hole radius, and core radius can be readily selected.
Q3. What are the design parameters for a terahertz waveguide?
Throughout the whole simulation 50% porosity, 1 THz frequency and x-polarization mode is considered as optimum design parameters.
Q4. What are the main types of waveguides that have been proposed earlier?
Metallic wires [6] and metal coated dielectric tubes[7] were proposed earlier but disregarded due to their higher bending loss and lower coupling efficiency.
Q5. What is the key to a highly birefringent fiber?
Beside low loss, it is also necessary to design a highly birefringent fiber that has key applications in terahertz sensing, communications, and terahertz heterodyne detection.
Q6. What are the techniques that can be used to fabricate asymmetrical optical structures?
Among them, capillary stacking, stack and drilling, sol-gel techniques are only capable of fabricating circular shaped air holes.
Q7. How many layers of elliptical structure have been proposed?
a birefringence value 1.19× 10−2 with high EML of 0.0689 cm−1 has been exhibited by applying two layers of elliptical structure in the core [18].
Q8. What is the method to fabricate asymmetrical optical fibers?
Microstructured optical fibers (MOFs) with different sizes of core and cladding air holes has already been fabricated using the extrusion technique [38], [39].
Q9. What is the effect of the reducing porosity on the EML?
It is also observed that, EML increases with the decrease of porosity because reducing porosity means reducing the core air hole diameter which in turn increase the amount of material inside the core area.
Q10. What is the EML as a function of frequency?
5. It can be observed that, as the frequency increases the EML also increases linearly which meets the theoretical consequences of calculating EML according to the empirical formula α(ν) = ν2+0.63ν−0.13 [dB/cm], [27].
Q11. What is the value of nco in the waveguide?
From the waveguide design, it can be observed that, the cladding mainly consists of a large number of air holes, thus most of the previously reported [24, 14] waveguides considered that value as unity, but practically the value should be greater than unity [27] because the cladding not only consists of air holes but also consists of bulk material.
Q12. what are potential applications in terahertz communication systems?
Potential applications are anticipated in the areas of sensing, terahertz communication systems and polarization preserving fibers.
Q13. Why is topas used as the background material?
Topas has been used as the background materialbecause of its unique characteristics including, lower bulk material absorption loss 0.2 cm−1; glass transition temperature
Q14. What is the description of the letter?
In this letter, the authors introduce a novel Topas based photonic crystal fiber consisting of a conventional hexagonal structure in the cladding and a penta-hole elliptical structure in the core which simultaneously offering ultra-high birefringence and ultra-low near zero flattened dispersion.
Q15. What is the dispersion of the fiber at optimal design parameters?
It can be seen that, at optimal design parameters the obtained dispersion is 0.53± 0.07 ps/THz/cm within a broad frequency range of 0.5–1.48 THz.
Q16. What are the characteristics of the proposed PCF?
It is clearly seen that, the proposed PCF shows excellent characteristics for polarization maintaining terahertz application in addition for flattened dispersion application.
Q17. What is the way to calculate birefringence?
Birefringence can be calculated using the following equation [28],B = |nx − ny| (1)where nx and ny represents the effective refractive index of x and y polarizations respectively.
Q18. What is the effective refractive index of Topas COC?
nmat is the effective refractive index of Topas COC, αmat is the bulk material absorption loss of Topas, 0 and µ0 is the relative permittivity and permeability of free space, Sz is the z-component of the Poynting vector Sz = 1 2 (E ×H ∗)z.
Q19. What is the elliptical air hole size?
ellipticity defined as the ratio of major and minor axis of the elliptical air holes (L/w) determines the size of the elliptical air holes.
Q20. What is the design parameter for a terahertz waveguide?
At optimal design parameters, the obtained birefringence is 0.086, which is better than the previously proposed [11, 12, 13, 14, 15, 16, 17, 18, 28] terahertz waveguides.
Q21. How much EML is obtained at optimal design parameters?
At optimal design parameters, a very small amount of EML of 0.05 cm−1 is obtained which is comparable with the previously reported [11, 12, 13, 14, 15, 16, 17, 18] fibers.
Q22. What is the f-component of the complex refractive index?
Im(neff) represents the imaginary part of the complex refractive index, f is the operating frequency and c is the speed of light.
Q23. What are the previous publications on elliptical air holes?
the previously published articles [34] [35] [36] reported that the elliptical air hole patterns can be fabricated using the existing fabrication technology.
Q24. What is the width of each air hole in the core?
The width (w) of each air hole in the core has been determined by the core porosity that can be defined as the fiber core area to the total area of the fiber.
Q25. What are the advantages of using 3D printed dies?
jiang et al.[30] recently used 3D printed dies and got improvement of fiber drawing over “stack and draw”and extruded preforms.