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Flat Fibers: Fabrication and Modal Characterization

  • Ghafour Amouzad MahdirajiEmail author
  • Katrina D. Dambul
  • Soo Yong Poh
  • Faisal Rafiq Mahamd Adikan
Living reference work entry

Abstract

This chapter presents the fabrication and modal characterization of flat fibers, a specialty optical fiber which has the advantages of both planar waveguides and standard optical fibers. In the introduction section, the demand for flat fibers is discussed including its applications. The main text of this chapter discusses the drawing process of flat fibers including issues such as flat fiber drawing repeatability and drawing of flat fibers with different dimensions. Next, the modal characterization of flat fibers is discussed, with a focus on the light propagation in flat fibers. Both simulation and experimental results show that the light propagation in flat fibers is inherently multimode propagation. However, it has been shown experimentally that adding two defect eyes at the sides of the core could produce flat fibers with single-mode propagation.

Keywords

Flat fibers Optical fiber fabrication Optical fibers characterization Multifunctional sensing fiber Single mode fiber 

Introduction

Optical fiber sensors can be used to detect physical changes in the environment surrounding the fiber. For example, a fiber biosensor can be used to detect the concentration of specific biological or chemical substance. However, the fiber sensor detection capability is limited as it can only detect a single specific target of sensing. Therefore, a combination of fiber sensors is often required to combine the optical signals (Zhang et al. 2013) and to allow multiple substances to be detected. The multifunctional property of planar waveguides gives rise to multipurpose usage in the same chip. In planar waveguides, light is guided on defined paths on a planar substrate. Planar waveguide is the basic component in integrated optic devices such as optical splitters, optical couplers, interferometers, and gratings (Buck 1995; Saleh and Teich 2007). Optical components such as couplers, filters, modulators, amplifiers, detectors, or even breakthrough diffraction limit plasmonics can be built on the same chip (Bian and Gong 2013). These optical devices can be fabricated on the flat surface of materials such as silica (Li and Henry 1996), silicon, semiconductor crystal, or plastic (Dutton 1998). However, the optical components often require advanced fabrication technology such as photolithography, UV writing, nonlinear resonators, and super-resolution imaging, quantum information, and light harvesting (Ferretti et al. 2013; Kildishev et al. 2013). Other fabrication methods for planar waveguides include etching and epitaxial growth (Singh 1996; Hunsperger 2009), but these methods are often costly and require a high precision (Dutton 1998). The limitations of planar waveguides are high propagation and coupling loss, rigid substrate and can be fabricated for only a short length (maximum of 10–15 cm).

An alternative solution to planar waveguides with added advantage of low propagation loss and high flexibility is fulfilled by a specialty optical fiber known as flat fiber (FF). FF was introduced in 2007 and was initially developed as alternative to planar waveguides due to its low-cost fabrication technique (Webb et al. 2007). The FF structure is almost similar to a buried channel planar waveguide, with a higher refractive index core layer and a lower refractive index at the cladding. The higher core refractive index allows light to continuously propagate inside the FF’s core via total internal reflection phenomena (Buck 1995; Kasap 2001). This unique fiber design fills the gap in integrated optic devices as a transport and sensing medium. FF can be described as a planar waveguide fiber with the advantages of having both optical fibers and planar waveguide’s properties, such as mechanically flexible, multifunctionality, long length fabrication, low coupling and propagation loss, etc. (Adikan et al. 2012). In addition, flat fibers also have the advantages of cylindrical optical fiber such as chemically inert, ability to withstand high ambient temperatures, and at the same time having a large flat surface area for material processing at low manufacturing costs (Kalli et al. 2015).

Due to the interesting properties of FF, there is a research demand and interest to develop technology for smart structures, integrated photonic circuits, and devices for optofluidic applications (Riziotis et al. 2014). Applications have been demonstrated via femtosecond laser micromachining, such as fabrication of optical structures, including ring and disk resonators and Mach-Zehnder interferometer. FFs solve the difficulties in producing substrate with such properties, where multistage process are required and the cost of manufacturing equipment limits the research area to well-funded groups (Duncan 2002; Scifres 1996).

Inscription of Bragg gratings, ring resonator, disc resonator, Mach-Zehnder interferometer, and microfluidic channel has been demonstrated on a FF using femtosecond laser inscription (Kalli et al. 2015). The inscription is done by having a focused beam from a femtosecond laser translated into a bulk transparent material which caused the refractive index of the core material to increase due to the nonlinear absorption process (Kalli et al. 2015).

Besides femtosecond laser, a more popular approach for developing optical/photonic devices on FFs is direct UV writing (Holmes et al. 2008; Adikan 2007). Studies were done to characterize UV-written (λUV = 244 nm) chips by studying the effective index value obtained from the grating experiment. Y-splitters/combiner, Bragg gratings, ring resonator, and straight channel are examples of devices that can be fabricated on FFs by using UV-written method (Adikan et al. 2012). Single beam direct UV writing can also be used to define waveguide channels in the core of FF (Holmes et al. 2008; Adikan 2007). But the core needs to be photosensitive and this can be done by doping the core with germanium and/or boron. Using direct grating writing where Bragg gratings are written on the core of the fiber and applying the principle of shifting the Bragg wavelength, evanescent field sensors have been demonstrated on FFs (Holmes et al. 2008).

The losses in FFs are not as low as cylindrical optical fibers and are typically in the region of 0.1 dB/m. However, this depends on its fabrication methods. Over the years, improvements have been made to realize this technology (Kalli et al. 2015). Flat fibers can also be cleaved quite efficiently, unlike its predecessor of planar silica on silicon samples which needs to be polished for laser inscription.

It is often desirable for lab-on-a-chip, optofluidics, and biosensor to “access” the guiding light so that the evanescent field can interact with an external fluid sample, typically for refractive index measurements. To improve the evanescent field in conventional fibers, in most of the cases, polishing of optical fibers to the core-cladding boundary is favored, a method which is very time consuming and inefficient. On the contrary, the potential of connecting the waveguide core with the surface using a femtosecond laser waveguide offers an alternative method that is less time consuming. In this case the “connection” distance between the core and surface is short, perhaps only 50 μm, and waveguide losses will not be significant. FF offers stronger evanescent field inherently due to the thinner cladding and much wider guiding area compared to conventional fiber and has the potential for fusion splicing with standard optical fiber as used in high-power fiber applications (Adikan et al. 2012).

Flat Fiber Fabrication

The fabrication of FFs begins with the fabrication of fiber preform. Nowadays, most preforms are fabricated using vapor deposition methods such as modified chemical vapor deposition (MCVD), outer vapor deposition (OVD), plasma-activated chemical vapor deposition (PAVD), and vapor axial deposition. These methods ensure quality and pureness of the preform during the dopant deposition process. Maintaining the purity of the preform minimizes the fiber attenuation due to absorption and scattering.

For fabrication of FF, a glass tube or hollow preform is used. The next stage of fabrication is to draw the hollow preform using a standard drawing tower. The drawing of FF is similar to other conventional optical fibers where the top end of the preform is clamped to the preform holder or feeder and the tip of the other end is placed inside the furnace. The motorized preform stage will slowly feed the preform down at a specified preform feeding speed into a furnace. The furnace typically uses a graphite heating element due to its thermal and mechanical properties (Payne and Gambling 1976). The condition inside the furnace should be maintained to be free from impurities and oxides built up since graphite has a high oxidation rate at high temperature. This can be done by purging the furnace with argon gas.

Next, the furnace will be heated to the preform’s softening temperature, which depends on the preform material and its dopants. When the preform surface temperature exceeds the preform’s softening temperature, the neck-down process occurs. The preform’s low viscosity from the high temperature combined with the deformation due to the draw tension and the force of gravity gradually reduces the preform’s diameter and the preform starts to drop down from the bottom of the furnace. The dropped part will be drawn by the fiber drawing tractor or capstan at a specified fiber drawing speed. The diameter of the fiber can be controlled based on the desired fiber diameter (dout), fiber drawing speed (vout), fiber preform outer diameter (Din), and the preform feeding speed (Vin) as shown in the following simplified mass conservation equation:
$$ {D}_{\mathrm{in}}^2{V}_{\mathrm{in}}={d}_{\mathrm{out}}^2{v}_{\mathrm{out}} $$
(1)

The neck-down profile is a function of the fiber drawing conditions such as furnace temperature, draw speed, feed speed and vacuum pressure, physical and material properties of the preform, and the type of heating element used in the furnace (Paek and Runk 1978; Choudhury and Jaluria 1998; Cheng and Jaluria 2002; Mawardi and Pitchumani 2010). It also determines the mechanical and optical characteristics of the optical fiber.

For the case of FF, since the preform is in a hollow form, the output fiber is initially in capillary form. Fabrication of FF begins when vacuum pressure is applied at the top of the hollow preform. As soon as vacuum pressure is applied, the preform neck-down region experiences vacuum force, causing the region to collapse or flatten. In this process, the circular capillary shape converts into flat shape, which is called flat fiber.

FF dimensions can be approximated (without considering the temperature effect) from the capillary dimensions. The thickness of the fabricated FF will be equal to the outer diameter of the capillary minus the inner diameter of the capillary. The width of the core is the inner radius of the capillary multiply with π and the width of the cladding will be equal to the width of the core and the thickness of the fiber.

FF can be drawn in two methods, either in single-stage or two-stage drawing. In single-stage drawing, a bulky hollow preform is directly drawn into a desired FF diameter. In this method, the diameter conversion rate from preform diameter to the output capillary diameter (or FF dimension) is very high, for example, drawing a 1 mm diameter capillary directly from a 25 mm diameter tube. In a two-stage method, a bulky size hollow tube preform is first drawn into a 2–3 mm diameter capillary and the same capillary is redrawn into the desired FF diameter, where the conversion ratio from the capillary to the final fiber is much smaller than that of single-stage FF fabrication.

Single-stage FF drawing method allows the fabrication of FF with a variety of dimensions by adjusting the drawing temperature or tension especially if a thick fiber core is required. Figure 1 shows an example of a thick FF with a dimension of 0.173 × 0.341 mm and a core width of 0.189 mm, which was fabricated using single-stage drawing method. The fiber was drawn directly from a hollow Ge-doped preform which has an OD/ID of 23 mm/15.4 mm at a furnace temperature of 2000 °C. However, it may be difficult to control the diameter of FF using single-stage drawing especially if a smaller diameter is required, for example, fabrication of a 125 μm fiber directly from a 25 mm preform.
Fig. 1

FF with a dimension of 0.173 × 0.341 mm fabricated in single-stage from a hollow Ge-doped preform with OD/ID of 23 mm/15.4 mm

The two-stage FF drawing method is more suitable for fabricating thinner cladding FF with a thinner core. Figure 2 shows an example of a FF fabricated in two-stage drawing method using the same preform used for the FF in Fig. 1. In this fabrication, the Ge-doped preform with OD/ID of 23 mm/15.4 mm was first drawn into a 3.75 mm diameter capillary, and in the second-stage drawing method, the 3.75 mm capillary is drawn into the desired FF with a dimension of 0.082 × 0.269 mm at a furnace temperature of 1960 °C with applied vacuum pressure of 5 kPa.
Fig. 2

FF with a dimension of 0.082 × 0.269 mm with a core width of 0.186 mm fabricated in two-stage from a Ge-doped preform with OD/ID of 23 mm/15.4 mm

Flat Fiber Drawing Repeatability

In general, the fabrication of FF is repeatable if all the fabrication parameters and the fiber preform used are similar. Fabrication of a FF with dimension of 0.385 × 0.107 mm is repeated over three times using a pure silica preform with an OD/ID of 25 mm/19 mm. The drawing parameters including furnace temperature, tension, vacuum pressure, feed rate, and draw speed were kept constant in all three experimental trials. The drawing parameters were first specified based on the drawing of a capillary with a 0.3 mm diameter. When the drawing of the capillary at this diameter has stabilized, vacuum pressure is then applied to ensure a consistent FF dimension. In each of the three experimental trials, seven samples were randomly selected from the drawn FFs. From a total of 21 samples, a maximum variation of around 5.5% (or ±2.7%) is observed in the FF dimensions. It should be noted that this variation is observed in the condition that the dimension of the fiber was not on the auto-control mode; instead, the system parameters were set once at the beginning of the fabrication till the end for all the three fabrication trials.

Flat Fibers with Different Dimensions

Five different dimensions of FFs were fabricated using the same Ge-doped preform. Two-stage drawing method was employed, where the preform was first drawn into a capillary with a diameter of around 3.8 mm and then this capillary was redrawn into five different dimensions of FFs. In this fabrication, the drawing tension for all fibers was fixed within 20–30 g and the vacuum pressure was varied from 5 kPa in the smallest dimension up to 10 kPa in the largest dimension. Dimensions of the five FFs were measured as 0.177 × 0.037 mm, 0.256 × 0.052 mm, 0.357 × 0.073 mm, 0.522 × 0.103 mm, and 0.762 × 0.154 mm as shown in Fig. 3a–e, respectively. The average width-to-thickness ratio of the FFs was around 4.87 with a variation of around ±2.56%. This shows consistent dimension ratio in fabricating different dimensions of FF using the same preform. It should be noted that due to insufficient vacuum pressure in these fabrications, the FFs were not fully collapsed along the fiber width and left two small defect holes in the structure.
Fig. 3

Five different dimensions of FFs fabricated from a 3.8 mm diameter capillary. Dimension of the fibers are (a) 0.177 × 0.037 mm, (b) 0.256 × 0.052 mm, (c) 0.357 × 0.073 mm, (d) 0.522 × 0.103 mm, (e) 0.762 × 0.154 mm

Characterization of Flat Fibers: Mode Propagation

Multimode Propagation in Flat Fibers

FFs are inherently multimode fibers. Mode propagation of the two FFs shown in Fig. 4 is analyzed in simulation using the software COMSOL Multiphysics. The mode profiles of both FFs obtained via simulation (Fig. 5) suggested multimode guidance mainly due to the large core area, as the modes are guided in both horizontal (nslow) and vertical (nfast) direction in the core.
Fig. 4

Example of ideal flat fiber with (a) thick core thickness of around 5 μm fabricated in single-stage and (b) thin core thickness of around 1.6 μm fabricated in two-stage

Fig. 5

Mode profile of the two FFs in Fig. 4. (a) Thick core thickness of around 5 μm and (b) thin core thickness of around 1.6 μm. (Inset) One of the possible guiding modes in the eye region

Tables 1 and 2 show the neff and power distribution per mode in the core and eye area in the 5 μm and 1.6 μm core thickness FFs, respectively. The results are calculated in power flow, time average (W/m2).

Referring to Table 1, for the FF core thickness of 5 μm as the power values imply, all modes from the fundamental to higher-order modes (up to 12) have high power in the FF core area. Referring to Table 2, for the FF core thickness of 1.6 μm, there is still a significant amount of power in the flat fiber core area from the fundamental to higher-order modes (up to 12) as well. These simulation results confirm that both FFs with thin or thick core are highly multimode fiber. This also signifies that even by reducing the core thickness, the multimode properties still exist in the slow axis, due to the wide dimensional area.

For validation, a simple test is performed on one of the FF used for the simulation above, i.e., the flat fiber with a thick core thickness of 5 μm. Figure 6 shows the mode operation in the FF captured by charged-coupled device at three different launching conditions, i.e., (a) incident light applied into the flat fiber’s left eye, (b) light applied into the center core, and (c) light applied into the right eye. It can be observed experimentally that the core and eyes were being guided in all three launching conditions. The fiber shows multimode operation in all launching conditions, as observed in the simulations shown in Fig. 5. By applying light into the FFs’ eye, light travels into the central core area as well as into the other eye area and vice versa. Even though light is applied with different launching positions, the mode operation of the FF always supports multimode propagation and does not reduce into single-mode operation.

Single-Mode Propagation in Flat Fibers

Single-mode propagation is observed in FF in a condition where a FF with two defect eyes, similar to the FF shown in Fig. 3e, and a high-index material (refractive index matching oil) is filled inside the defect eye hole. Now, by considering a refractive index difference between the matching oil in the defect eye holes compared to the central core, the simulated mode propagation in the central core of the FF would be as presented in Fig. 7. The mode propagation in Fig. 7 suggests that by applying a suitable (higher) refractive index in the eye holes compared to the fiber central core, the fiber tends to show a single-mode operation. The higher-order modes in this condition are effectively leaked into the eyes.
Table 1

neff and power distribution per mode in the FF core and eye area for the 5 μm core thickness

 

neff

ncore (W/m2)

neye (W/m2)

Fundamental mode

1.445405

335.2701

0.9709

Second-order mode

1.445401

333.5621

3.4509

Third-order mode

1.445395

331.4029

6.5269

Twelfth-order mode

1.445237

322.3463

20.521

Table 2

neff and power distribution per mode in the FF core and eye area for the 1.6 μm core thickness

 

neff

ncore (W/m2)

neye (W/m2)

Fundamental mode

1.444272

80.7868

2.6213

Second-order mode

1.444268

79.6326

7.5825

Third-order mode

1.444262

78.7959

11.5385

Twelfth-order mode

1.444097

77.6759

15.0127

Fig. 6

Mode operation in 5 μm core thickness FF measured experimentally at 1550 nm, where the incident light applied from three different launching positions of the FF core. (a) Light applied into the left eye area, (b) light applied into the central core area, and (c) light applied into the right eye area

Fig. 7

Mode propagation in the proposed flat fiber with two defect holes where the holes are filled with optimum refractive index of 1.44550

Fig. 8

Various launching conditions for the FF with defect air holes. (a) Light applied from left eye hole, (b) light applied into the fiber central core area, and (c) light applied from the right eye hole. Figures (e), (f) and (g) show the respective launching image captured by charged-coupled device (Poh et al. 2017)

Fig. 9

Mode profiles before and after oil infiltration into the FF air holes. Insets show charged-couple device images captured (a) before and (b) after oil infiltration (Poh et al. 2017)

The simulation results in Fig. 7 seems to suggest that the higher-order modes after leaking into the eyes were trapped there and not returning back into the central core area. This phenomenon that exists in this FF has never been observed in the ideal FFs. This phenomenon is further clarified by experimental results as seen in Fig. 8.

Figure 8 depicts three different launching conditions of SMF coupled into the FF with defect eye holes (without filling the index matching oil inside the defect holes) (Poh et al. 2017). In Fig. 8a, c, light was launched into the fiber’s left and right eyes, respectively. It was observed that the light propagating from the eye area does not propagate into the FF central core area. This was unlike what was observed in the ideal FF without defect eye holes presented in Fig. 6. Figure 8b shows the launching condition into the FF central core area. In this experiment, the incident light from the SMF is being moved slightly from one end to another end of the central core. In all swiping positions, the light propagating from the central core area never travelled into the eyes unlike as observed in the FF without defect eye holes shown in Fig. 6. However, in all conditions, the resulting mode guidance in the central core was always multimode as shown in Fig. 8f.

By applying a higher index matching oil into the FF’s eye holes, the multimode propagation in the FF reduces to single-mode operation as illustrated in Fig. 9. The dotted red curves in Fig. 9 depicts a multimode behavior measured in the FF before oil infiltration in the eye holes. In this condition, light is strongly confined in both the fast and slow axis of the FF. As soon as the FF eye holes were filled with refractive index matching oil, the higher-order modes were successfully reduced as shown by the solid green lines. It could be possible that the higher-order modes are attenuated through leaky mode mechanism and reduced to single-mode operation.

Conclusion

Fabrication of flat fiber is shown to be practically feasible using the conventional fiber drawing tower. Fabrication of this fiber is shown to be repeatable with a variation of around ±2.7% by employing the same drawing parameters and the preform material. FFs with different dimensions but almost similar width-to-thickness ratio (±.56% variation) can be fabricated by keeping the drawing tension constant. FFs with variety of dimensions can be fabricated when the drawing conversion from preform diameter to the fiber dimension is large and by varying the drawing tension or furnace temperature. FFs have inherently multimode propagation due to large core area or core width. However, single-mode FF is shown to be possible by applying a suitable refractive index material in the FF eye holes. This material would be either liquid form for short fiber length or would be a glass rod (with slightly higher refractive index than the FF central core) placed in the fiber during the FF fabrication. FFs would be a good alternative to planar waveguide with the advantages of flexibility, long fabrication feasibility, lower loss and ease of cleaving.

References

  1. F.R.M. Adikan, Direct UV-Written Waveguide Devices (University of Southampton, Southampton, 2007)Google Scholar
  2. F.R.M. Adikan, S.R. Sandoghchi, Y. Chong Wu, R.E. Simpson, M.A. Mahdi, A.S. Webb, J.C. Gates, C. Holmes, Direct UV written optical waveguides in flexible glass flat fiber chips. Sel. Top. Quant. Electron., IEEE J. 18, 1534–1539 (2012)CrossRefGoogle Scholar
  3. Y. Bian, Q. Gong, Multilayer metal–dielectric planar waveguides for subwavelength guiding of long-range hybrid plasmon polaritons at 1550 nm. J. Opt. 16, 015001 (2013)CrossRefGoogle Scholar
  4. J.A. Buck, Fundamentals of Optical Fibers, (Wiley, 1995)Google Scholar
  5. X. Cheng, Y. Jaluria, Effect of draw furnace geometry on high-speed optical fiber manufacturing. Numer. Heat Transf. A: Appl. 41, 757–781 (2002)CrossRefGoogle Scholar
  6. S.R. Choudhury, Y. Jaluria, Practical aspects in the drawing of an optical fiber. J. Mater. Res. 13, 483–493 (1998)CrossRefGoogle Scholar
  7. H. Duncan, Fabrication of substrates for planar waveguide devices and planarwaveguide devices, Google Patents, (2002)Google Scholar
  8. H.J. Dutton, Understanding Optical Communications (Prentice Hall PTR, New Jersey, 1998)Google Scholar
  9. S. Ferretti, V. Savona, D. Gerace, Optimal antibunching in passive photonic devices based on coupled nonlinear resonators. New J. Phys. 15, 025012 (2013)CrossRefGoogle Scholar
  10. C. Holmes, F.R.M. Adikan, A.S. Webb, J.C. Gates, C.B. Gawith, J.K. Sahu, P.G. Smith, D.N. Payne, Evanescent Field Sensing in Novel Flat Fiber (Optical Society of America, 2008), pp. CMJJ3Google Scholar
  11. R.G. Hunsperger, Integrated Optics Theory and Technology (Springer, Berlin, 2009)Google Scholar
  12. K. Kalli, C. Riziotis, A. Posporis, C. Markos, C. Koutsides, S. Ambran, A.S. Webb, C. Holmes, J.C. Gates, J.K. Sahu, P.G.R. Smith, Flat fibre and femtosecond laser technology as a novel photonic integration platform for optofluidic based biosensing devices and lab-on-chip applications: Current results and future perspectives. Sensors Actuators B Chem. 209, 1030–1040 (2015)CrossRefGoogle Scholar
  13. S.O. Kasap, Optoelectronics and Photonics: Principles and Practices (Pearson, Boston, 2001)Google Scholar
  14. A.V. Kildishev, A. Boltasseva, V.M. Shalaev, Planar photonics with metasurfaces. Science 339, 1232009 (2013)CrossRefGoogle Scholar
  15. Y.P. Li, C.H. Henry, Silica-based optical integrated circuits. IEE Proc. Optoelectron. 143, 263–280 (1996)CrossRefGoogle Scholar
  16. A. Mawardi, R. Pitchumani, Optical fiber drawing process model using an analytical neck-down profile. IEEE Photonics J 2, 620–629 (2010)CrossRefGoogle Scholar
  17. U. Paek, R. Runk, Physical behavior of the neck-down region during furnace drawing of silica fibers. J. Appl. Phys. 49, 4417–4422 (1978)CrossRefGoogle Scholar
  18. D.N. Payne, W.A. Gambling, A resistance-heated high temperature furnace for drawing silica-based fibres for optical communications. Am. Ceram. Soc. Bull. 55, 195–197 (1976)Google Scholar
  19. S.Y. Poh, G.A. Mahdiraji, Y.M. Sua, F. Amirkhan, D.C. Tee, K.S. Yeo, F.R.M. Adikan, Single-mode operation in flat fibers slab waveguide via modal leakage. IEEE Photonics J 9, 1–9 (2017)CrossRefGoogle Scholar
  20. C. Riziotis, K. Kalli, C. Markos, A. Posporis, C. Koutsides, A.S. Webb, C. Holmes, J.C. Gates, J.K. Sahu, P.G.R. Smith, Flexible glass flat-fibre chips and femtosecond laser inscription as enabling technologies for photonic devices. At Photonics West (2014), United States, pp. 89820G–89820G-89828Google Scholar
  21. B.E. Saleh, M.C. Teich, Semiconductor photon detectors. Fundam. Photonics, 644–695 (2007)Google Scholar
  22. D.R. Scifres, C.A. San Jose, Multiple core fiber laser and optical amplifier, Google Patents, United States Patent 5566196, Application Number: 08/330262 (1996)Google Scholar
  23. J. Singh, Optoelectronics: An Introduction to Materials and Devices (McGraw-Hill College, New York, 1996)Google Scholar
  24. A. Webb, F.R.M. Adikan, J. Sahu, R. Standish, C. Gawith, J. Gates, P.G. Smith, D. Payne, MCVD planar substrates for UV-written waveguide devices. Electron. Lett. 43, 517–519 (2007)CrossRefGoogle Scholar
  25. X. Zhang, A. Hosseini, X. Lin, H. Subbaraman, R.T. Chen, Polymer-based hybrid-integrated photonic devices for silicon on-chip modulation and board-level optical interconnects. Sel. Top. Quant. Electron., IEEE J. 19, 196–210 (2013)CrossRefGoogle Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  • Ghafour Amouzad Mahdiraji
    • 1
    • 2
    Email author
  • Katrina D. Dambul
    • 3
  • Soo Yong Poh
    • 4
  • Faisal Rafiq Mahamd Adikan
    • 2
    • 4
  1. 1.School of EngineeringTaylor’s UniversitySubang JayaMalaysia
  2. 2.Flexilicate Sdn. Bhd.University of MalayaKuala LumpurMalaysia
  3. 3.Faculty of EngineeringMultimedia UniversityCyberjayaMalaysia
  4. 4.Integrated Lightwave Research Group, Department of Electrical Engineering, Faculty of EngineeringUniversity of MalayaKuala LumpurMalaysia

Section editors and affiliations

  • H. A. Abdul-Rashid
    • 1
  1. 1.Faculty of EngineeringMultimedia UniversityCyberjayaMalaysia

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