A miniaturized tunable optical attenuator with ultrawide bandwidth based on evanescent-field coupling between nanofibers | Scientific Reports

Scientific Reports volume 14, Article number: 18503 (2024) Cite this article

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We propose a novel miniaturized optical attenuator based on the evanescent-field coupling between two nanofibers. Benefiting from a wavelength-dependent waveguiding property of the coupled structure, a tunable attenuation with maximum extinction ratio of ~ 20 dB is demonstrated with an ultrawide optical bandwidth up to 0.7 μm in experiment. The wavelength-depended waveguiding properties of both one single nanofiber and coupled nanofibers are investigated in both theory and simulation. Using an adiabatic coupling structure, an attenuation range from − 0.16 dB to − 18.46 dB is obtained within a spectrum from 1.2 μm to 1.7 μm experimentally. Moreover, the simulated results indicate that, the attenuation only shows a slight change of ~ 0.1 dB with a lateral misalignment of 0.5 μm between the two nanofibers, indicating a high tolerance of this attenuator to the lateral misalignment. Considering the wide bandwidth as well as the ultracompact structure, this attenuator shows high potential in applications such as all-fiber optical sensing and communicating.

The miniaturized optical attenuator has been proven to be an essential component in optical communication system1. In recent years, various tunable optical attenuation methods based on different principles such as refractive index change2,3, acousto-optic effect4, optical field reflection5, and evanescent field coupling6,7, have been reported. Among these methods, the approach based on nanofibers has gained significant attention due to its simple structure, high-cost effectiveness, and high compatibility to optical fiber networks8. Typically, nanofiber-based approaches rely on the modulation of the material refractive index or the mechanical stretching9. The light-controlled optical fiber, composed of an optically responsive liquid crystal coating, achieves attenuation through photochemically induced liquid crystals phase transition2,3,10. In 2009, Hsiao et al. by controlling the illumination, it is possible to achieve optical attenuation within a wavelength range of 5 nm. In 2005, Jeong et al. reported the achievement of optical attenuation across a wavelength range of 100 nm by employing a microactuating platform to alter the refractive index at the waist of a fused taper fiber11. In 2010, Lim reported achieving optical attenuation within a wavelength range of 70 nm by fabricating a microfiber into an optical fiber Sagnac interferometer and changing the coupling ratio through optical refraction12. The fiber is adhered to a pre-stretched substrate and subsequently released to induce prestrain. Due to the constraints of the substrate, the fiber bends into a sinusoidal waveform. In 2022, Yuhan Wang et al. reported that stretching the substrate allows for optical attenuation within a wavelength range of approximately 10 nm13. Moreover, by combining a movable optical reflector with a fixed desired thin-film filter. In 2018, Georgescu et al. reported that a cascaded multi-wavelength attenuator can be formed using thin-film filters and mechanically movable mirrors, with a wavelength range of up to 100 nm14. Limited by a confined changing range of refractive index or mechanical structure, the typical optical bandwidth is less than 100 nm. Considering the recent interest in developing integrated optical communicating systems with higher optical communication capacity, nanofiber-based optical attenuator with much wider bandwidth is in high demand15.

Benefitting from the sub-wavelength-sized structures, nanofibers show strong optical confinement with low propagating losses16. Using an evanescent field, the coupling efficiency between nanofibers can be up to more than 90% in the telecommunication band17. Nanofiber-based couplers have been widely used in applications ranging from lasing and optical sensing18,19,20,21,22. It is found that the coupling efficiency is highly related to the coupling length within a wide optical spectrum. As a result, by changing the overlap length between two nanofibers, it is possible to modulate the transmitted spectra with an expanded bandwidth.

In this paper, an ultrawide-bandwidth optical attenuator based on the evanescent-field coupling between two nanofibers is demonstrated. Using an evanescent field, broadband input light can be coupled from a tapered nanofiber to a uniform nanofiber through an adiabatic coupling process. As a result of the gradually varied diameter along the tapered nanofiber, the fundamental mode of the component for the input light with different wavelength will be cut off at different positions along the nanofiber. As a result, by changing the coupling length between the two nanofibers, the transmitted spectra change as well. Both the theoretical and the simulated results show a tunable optical bandwidth up to 0.7 μm (from 1.2 μm to 1.9 μm) with a maximum extinction ratio of ~ 15 dB. The simulated results also demonstrated a high tolerance to small lateral misalignments (e.g. ~ 0.1 dB change in attenuation with a lateral misalignment of 0.5 μ m). We believe that the proposed all-fiber attenuator show well potential in applications ranging from optical communication to optical sensing.

The schematic diagram of the nanofiber-based attenuator is shown in Fig. 1. The nanofibers are both fabricated by adiabatic tapering method23. The broadband input light propagating along the tapered fiber is coupled into a uniform fiber through an evanescent-field coupling process. The transmitted spectra are analyzed by a spectrograph15. The integration of the two fibers is ensured through van der Waals forces and electrostatic forces. A pigtail structure is used in uniform fiber to avoid the influence of end-face reflection. The diameter of the tapered fiber is carefully designed to meet the adiabatic waveguiding condition. By changing the coupling length (L) between the two nanofibers, the transmitted spectra change as well.

Schematic diagram of the attenuator. The broadband input light is coupled from a tapered nanofiber to a uniform nanofiber through an adiabatic coupling process.

The nanofiber is manufactured from SMF-28 standard optical fiber. The refractive index of the fused silica (SiO2) air-clad cylindrical nanofiber can be given by24

where \(\lambda \) represents the wavelength with units in μm, n1 is the refractive index of SiO2.

Using Eq. (1), the cutoff diameter (D) of the fundamental mode at different wavelengths can be expressed as24

where n2 is the refractive index of air (which is 1.0), V = 2.405 is the normalized frequency. The single-mode condition of the nanofiber is shown in Fig. 2. The red line and the black line indicate the cut-off condition of HE12 and HE11 modes, respectively. The shadow region within the two lines shows the single-mode condition. To ensure a single-mode waveguiding through wavelength from 1 μm to 2.5 μm, the diameter of the nanofiber should be below 1.2 μm.

The single-mode waveguiding condition of a nanofiber at different wavelength. The red line and the black line indicate the cut-off condition of HE12 and HE11 mode respectively, the shaded region represents the single-mode diameter region of the nanofiber.

The tunable bandwidth of the proposed attenuator is based on the coupling-length-dependent transmission properties of the two nanofibers. As shown in Fig. 3a, for the tapered nanofiber, the minimum diameter required to support the fundamental mode increases with a larger wavelength . The average varying angle of the tapered nanofiber is 0.19°. The black arrows indicate the attenuating region at different wavelengths, in which the waveguiding mode changing into spatial light modulation, resulting in a gradually decreasing transmission. For example, at a wavelength of 1.2 μm, the transmission changes from -0.1 dB to -25 dB as diameter changing from 0.5 μm to 0.09 μm. As shown in Fig. 3b, since the initial diameter of the coupling process differs as the coupling length changes, a tunable transmission can be obtained by changing the coupling length. For example, light with wavelength through from 1.2 μm to 1.9 μm can be transmitted with a coupling length of 221 μm. However, as coupling length decreasing (e.g., to 45.5 μm), the long-wavelength component of the input light is cut off, resulting narrowing the bandwidth of the coupled light (e.g., wavelength from 1.9 μm to 1.55 μm).

(a) The cut-off wavelength of the tapered nanofiber. The minimum diameter required to support the fundamental mode increases with a larger wavelength. (b) The initial diameter of the coupling process changes with the coupling length.

The propagating process is analyzed by a finite-difference time-domain (FDTD) method. The tapered nanofiber used in the simulation has a initial diameter of 1 μm and a varying angle of 0.19°. The propagating process for the tapered nanofiber at different wavelength is shown in Fig. 4. As the diameter gradually decreases, the energy of waveguiding modes with longer wavelength no longer satisfies the single-mode waveguiding condition, leading to a significant loss. For example, 1.9 μm-wavelength light losses around the position at 30 μm. For a shorter wavelength at 1.2 μm, its losses around the position at 150 μm, corresponding to a smaller diameter. The transmission decreases for different wavelengths shown in Fig. 5, within the diameter range of 0.5 to 0.19 μm, from 1.9 μm to 1.2 μm wavelength range.

The propagating process for the tapered nanofiber at different wavelength of (a) 1.2 μm, (b) 1.55 μm and (c) 1.9 μm respectively. The dashed lines indicate the position of the nanofiber.

The transmission properties of the tapered nanofiber at different wavelength with a changing diameter is shown in Fig. 5. In region I, as diameter decreasing, the transmission at long wavelength decreases while the transmission at shorter wavelength remains unchanged. In this case, the coupler is operated as a tunable short-pass filter. In region II, the transmission of different wavelengths decreases with an almost same rate of 40 dB/μm with a decreasing diameter, which can be used as a optical attenuator.

The transmitted spectra of a tapered nanofiber at different wavelength with a changing diameter.

The coupling properties between the two nanofibers with different initial diameters and wavelengths are shown in Fig. 6. The taper fiber has an initial diameter of 1 μm, an angle of 0.19°s, and the uniform fiber has a diameter of 0.6 μm. The results demonstrate that, with different initial diameters by changing the coupling length, the transmitted properties change as well.

Transmitted properties between two nanofibers with different initial diameters and wavelengths.

The simulated transmitted spectra are shown in Fig. 7. By decreasing the coupling length from 300 μm to 0 μm, the transmitted amplitude over a bandwidth from 1.2 μm to 1.9 μm decreases at meanwhile (as shown in Fig. 7a). For example, with a coupling length of 65 μm, the normalized transmission at 1.2 μm and 1.9 μm wavelength are − 8.7 dB and − 12.4 dB respectively. However, as the coupling length increases to 300 μm, the transmission changes to − 0.03dB @1.2 μm and − 0.06 dB @1.9 μm. The maximum extinction ratio is obtained to be ~ − 15 dB over a bandwidth of 700 nm (as shown in Fig. 7b).

The normalized simulated transmission spectra. (a) The simulated transmitted spectra with different coupling lengths across a spectrum from 1.2 μm to 1.9 μm. (b) The simulated transmission spectra at different wavelengths with an increasing coupling length.

The influence of the lateral misalignment is also analyzed simultaneously (as shown in Fig. 8). When the two fibers are tightly aligned, input light can be coupled into the uniform nanofiber with a high transmission (e.g., loss <-0.15 dB) at a coupling length is 260 μm. The initial diameter of the tapered nanofiber and the diameter of the uniform nanofiber is 0.9 μm and 0.6 μm respectively. Assuming that H is the axial misalignment distance between the two nanofibers. As H changing from 0 μm to 0.5 μm, a slight change within − 0.11 dB is obtained. This can be explained by the high overlap between the evanescent fields as the diameter of the nanofiber is relatively small. The results indicate a well tolerance of the attenuator to small lateral misalignments.

The influence of the lateral misalignment on the transmission.

We have simulated the optical transmission with different surrounding refractive index. As shown in Fig. 9, the optical transmission of two nanofiber with a coupling length of 300 μm remains almost unchanged for different surrounding refractive index of 1.0 and 1.1 respectively. For example, the transmission at 1.8 μm wavelength are -0.14 dB and -0.16 dB respectively for refractive index of 1.0 and 1.1. The results indicate a high stability for the devices to the fluctuation of the surrounding refractive index caused by factors such as temperature and humidity fluctuations.

Optical transmission with different surrounding refractive index.

As shown in Fig. 10, the optical transmission with wavelength ranging from 1.2 μm to 1.9 μm with different polarization states of TEM, TE and TM is simulated. The results demonstrate that, the optical transmission remains almost unchanged with different polarization states. For example, a transmission of − 0.104 dB, − 0.107 dB and − 0.108 dB are obtained for TEM, TE and TM cases respectively at wavelength of 1.65 μm. The inset figures show the transmitted properties between the two nanofibers at polarization states of TEM, TE and TM respectively at wavelength of 1.65 μm, indicating a similar transmitting process.

Optical transmission of light with different polarization states. Inset show the transmitted properties between the two nanofibers at polarization states of TEM, TE and TM respectively at wavelength of 1.65 μm.

To avoid optical loss caused by the coupling between different waveguiding modes, the tapered nanofiber should be operated in an adiabatic waveguiding condition. When the diameter of the fiber is large (e.g., > 50 μm), energy transmission in the fiber is primarily guided by the core-cladding interface for the fundamental mode25, the adiabatic condition is determined by the coupling between the HE11 and HE12 cladding-guided modes. When the diameter of the fiber is small enough (e.g., < 50 μm), the fundamental mode is predominantly guided by the cladding-air interface. Fig. 11a shows the critical angle of the tapered fiber for the adiabatic waveguiding condition with different diameters at wavelengths of 1.2 μm and 1.9 μm respectively. The adiabatic waveguiding condition is satisfied when the profile of the fiber falls below the shadow region. For example, when the wavelength is 1.2 μm and the diameter of the nanofiber is 30 μm, a varying angle below 1.52°s is required.

The nanofibers are prepared using a flame-heating rapid stretching process from SMF-28 fiber26. We measured the diameter of the tapered nanofiber by both optical microscopy and scanning electron microscopy (SEM). For example, a diameter of 0.66 μm is obtained (as shown in Fig. 11b). The results show that the diameter of the tapered nanofiber gradually changes from 125 μm to 0.4 μm. And the diameter of the uniform nanofiber is measured to be 0.66 μm (as shown in Fig. 11c). The varying angle of the tapered nanofiber is calculated and indicated by the dash line in Fig. 11a. The results indicate that the nanofiber can be used for adiabatic waveguiding and coupling processes.

(a) The adiabatic condition of the nanofiber. The condition is satisfied as the profile of the nanofiber is below the shaded area. The different colors of the shadow regions correspond to wavelengths of 1.2 μm and 1.9 μm respectively. The profile of the nanofiber used in the experiment is indicated by a dash line. When the diameter is less than 2.1 μm and 1.2 μm, the HE12 mode corresponding to wavelengths of 1.9 μm and 1.2 μm is cut off. (b) SEM image of the tapered nanofiber at diameter of 3.68-4.13 μm. (c) SEM image of the uniform nanofiber with diameter of 0.66 μm.

The light source used in the experimental system is a supercontinuum laser (SC-5, Yangtze Soton Laser) with an output spectrum from 400 to 2400 nm. The nanofiber is located on displacement stages (BSS16-60, Suruga). The transmitted spectra are measured by a spectrometer (Q8344A, Advantest). The axial alignment are ensured by a micromanipulation process using optical tapers16.The coupling structure of the two nanofibers suspend in air are shown in Fig. 12. The coupling length is ~ 150 μm. And the coupling length can be changed by moving the displacement stages.The exact positions of the two nanofibers as well as the coupling length can be obtained by observing the scattering points at the end of the two nanofibers in the optical images. The measuring resolution is determined by the resolution of the optical microscope to be several hundreds of nanometers.

Coupling microscope photo of nanofiber.

The normalized transmitted spectra with different coupling lengths are shown in Fig. 13. In the experiment, the initial coupling length between the two nanofibers is 300 μm. Limited by the measuring range of the spectrometer, the spectra with wavelength across 1.2 to 1.7 μm are measured. When the coupling lengthgradually decreases from 300 μm to 25 μm, the transmission decreases as well. The experimental results show a maximum extinction ratio of ~ − 18 dB. For example, when the coupling length changes from 150 μm to 25 μm, the transmitted intensity at 1.3 μm wavelength decreases from − 7.47 dB to − 20.4 dB, corresponding to an attenuation of 12.93 dB. At the same time, the transmitted intensity at 1.7 μm wavelength decreases from − 8.28 dB to − 24.5 dB, corresponding to an extinction ratio of 16.22 dB. The stronger attenuation at longer wavelength may be explained by a stronger loss with a same diameter. As the diameter of the nanofiber changes by 0.1 μm, the coupling length changes by ~ 50 μm, corresponding to a change in the extinction ratio of 3.28 dB. The result indicates a rate of ~ 32.8 dB/μm, which is comparable to the simulated results. The difference between the experimental and the simulated results, including a fluction within 2.73 dB in experimental results, can be explained by the non-ideal drawing during the fabrication of the nanofibers. And the dusts attached on the surface of the nanofibers also result in additional losses by optical scattering.

The transmitted spectra across 500 nm bandwidth with different coupling lengths.

We prosed a miniaturized tunable optical attenuator with ultrawide bandwidth based on nanofibers. Using evanescent coupling between a tapered nanofiber and an uniform nanofiber, the transmission can be effectively modulated by changing the coupling length. Both simulated and experimental results indicate a maximum extinction ratio more than 15 dB within a wide optical bandwidth over 500 nm. Moreover, the influence of the lateral misalignment on the transmission is also analyzed simultaneously, demonstrating a well tolerance for the proposed attenuator to small lateral misalignment. Considering that the high-precision and repeatable fabrication of nanofibers with a geometry control precision down to nanometer level has already been demonstrated and reported27, a high reproducibility is expected.The results demonstrate an ultrawide bandwidth with a tunable attenuation, indicating. the great potential of this attenuator in applications ranging from optical communication to optical sensing.

Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the corresponding author upon reasonable request.

Werner, S., Navaridas, J. & Luján, M. A survey on optical network-on-chip architectures. ACM Comput. Surv. 50, 1–37 (2017).

Article Google Scholar

Hsiao, V. K., Li, Z., Chen, Z., Peng, P.-C. & Tang, J. Optically controllable side-polished fiber attenuator with photoresponsive liquid crystal overlay. Opt. Express 17, 19988–19995 (2009).

Article ADS CAS PubMed Google Scholar

Hanson, E. G. Polarization-independent liquid-crystal optical attenuator for fiber-optics applications. Appl. Opt. 21, 1342–4 (1982).

Article ADS CAS PubMed Google Scholar

Riza, N. A. & Mughal, M. J. Fiber-optic tunable multiwavelength variable attenuator and routing module designs that use bulk acousto-optics. Appl. Opt. 44, 792–799 (2005).

Article ADS PubMed Google Scholar

Sumriddetchkajorn, S. & Chaitavon, K. Wavelength-sensitive thin-film filter-based variable fiber-optic attenuator with an embedded monitoring port. IEEE Photonics Technol. Lett. 16, 1507–1509 (2004).

Article ADS Google Scholar

Yu, W. et al. Highly sensitive and fast response strain sensor based on evanescently coupled micro/nanofibers. Opto-Electron. Adv. 5, 210101–1 (2022).

Article CAS Google Scholar

Ji, Y., Chen, Y., Sun, D., Zhang, G. & Zhu, X. An all-fiber optical attenuator based on adjustable coupling angle of microfiber. Opt. Commun. 486, 126771 (2021).

Article CAS Google Scholar

Wu, X. & Tong, L. Optical microfibers and nanofibers. Nanophotonics 2, 407–428 (2013).

Article ADS Google Scholar

Lotem, H., Eyal, A. & Shuker, R. Variable attenuator for intense unpolarized laser beams. Opt. Lett. 16, 690–2 (1991).

Article ADS CAS PubMed Google Scholar

Maese-Novo, A. et al. Thermally optimized variable optical attenuators on a polymer platform. Appl. Opt. 54, 569–575 (2015).

Article ADS CAS Google Scholar

Jeong, Y. S., Bae, S. C., Jung, Y. & Oh, K. Micro-optical waveguide on micro-actuating platform and its application in variable optical attenuator. Opt. Fiber Technol. 12, 38–47 (2006).

Article ADS Google Scholar

Lim, S. D., Lee, S. G., Lee, K. & Lee, S. B. A tunable-transmission sagnac interferometer using an optical microfiber. Jpn. J. Appl. Phys. 49, 082502 (2010).

Article ADS Google Scholar

Wang, Y.-H., Xu, Z.-L., Wang, Y., Jiang, H. & Chuang, K.-C. Buckling-induced wavy optical fiber attenuator. Opt. Lett. 47, 4845–4848 (2022).

Article ADS PubMed Google Scholar

Georgescu, T. S., Dancus, I. & Ursescu, D. Free space variable optical attenuator using frustrated total internal reflection with 70 db dynamic range. Appl. Opt. 57, 10051–10055 (2018).

Article ADS CAS PubMed Google Scholar

Cunningham, D. G. & White, I. H. Advances in local area optical data communication systems. Rep. Progr. Phys. 83, 075101 (2020).

Article ADS CAS Google Scholar

Guo, X., Ying, Y. & Tong, L. Photonic nanowires: From subwavelength waveguides to optical sensors. Acc. Chem. Res. 47, 656–666 (2014).

Article CAS PubMed Google Scholar

Chen, B., Wu, H., Xin, C., Dai, D. & Tong, L. Flexible integration of free-standing nanowires into silicon photonics. Nat. Commun. 8, 20 (2017).

Article ADS CAS PubMed PubMed Central Google Scholar

Jiang, X. et al. Demonstration of microfiber knot laser. Appl. Phys. Lett. 89, 143513 (2006).

Article ADS Google Scholar

He, X. et al. Passively mode-locked fiber laser based on reduced graphene oxide on microfiber for ultra-wide-band doublet pulse generation. J. Lightwave Technol. 30, 984–989 (2012).

Article ADS CAS Google Scholar

Coillet, A., Cluzel, B., Vienne, G., Grelu, P. & de Fornel, F. Near-field characterization of glass microfibers on a low-index substrate. Appl. Phys. B 101, 291–295 (2010).

Article ADS CAS Google Scholar

Wang, S., Pan, X. & Tong, L. Modeling of nanoparticle-induced Rayleigh–Gans scattering for nanofiber optical sensing. Opt. Commun. 276, 293–297 (2007).

Article ADS CAS Google Scholar

Joel, V. & Monzón-Hernández, D. Fast detection of hydrogen with nano fiber tapers coated with ultra thin palladium layers. Opt. Express 13, 5087–5092 (2005).

Article ADS Google Scholar

Yao, N. et al. Ultra-long subwavelength micro/nanofibers with low loss. IEEE Photonics Technol. Lett. 32, 1069–1072 (2020).

Article ADS Google Scholar

Tong, L., Lou, J. & Mazur, E. Single-mode guiding properties of subwavelength-diameter silica and silicon wire waveguides. Opt. Express 12, 1025–1035 (2004).

Article ADS CAS PubMed Google Scholar

Love, J. et al. Tapered single-mode fibres and devices. Part 1: Adiabaticity criteria. IEE Proceed. J. (Optoelectronics) 138, 343–354 (1991).

Article Google Scholar

Xu, Y., Fang, W. & Tong, L. Real-time control of micro/nanofiber waist diameter with ultrahigh accuracy and precision. Opt. Express 25, 10434–10440 (2017).

Article ADS CAS PubMed Google Scholar

Kang, Y. et al. Ultrahigh-precision diameter control of nanofiber using direct mode cutoff feedback. IEEE Photonics Technol. Lett. 32, 219–222 (2020).

Article ADS CAS Google Scholar

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National Natural Science Foundation of China (no.62375247).

School of Instrument and Electronics, North University of China, Taiyuan, 030051, China

Changjiang Fan, Yunfei Zhang, Lijun Guo, Mengwei Li & Chenguang Xin

State Key Laboratory of Extreme Photonics and Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310027, China

Jianbin Zhang

School of Instrument and Intelligent Future Technology, North University of China, Taiyuan, 030051, China

Mengwei Li & Chenguang Xin

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C.F. conceived the idea. C.F., M.L., and C.X. supervised the study. J.Z. processed the optical fiber. C.F. and Y.Z. conducted the numerical simulations and experiment. C.F. and L.G. analyzed the results. All authors reviewed the manuscript.

Correspondence to Mengwei Li or Chenguang Xin.

The authors declare no competing interests.

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Fan, C., Zhang, Y., Zhang, J. et al. A miniaturized tunable optical attenuator with ultrawide bandwidth based on evanescent-field coupling between nanofibers. Sci Rep 14, 18503 (2024). https://doi.org/10.1038/s41598-024-69407-2

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Received: 06 January 2024

Accepted: 05 August 2024

Published: 09 August 2024

DOI: https://doi.org/10.1038/s41598-024-69407-2

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