The loss formula for optical fibers with constant radius of curvature of their axes. A new bend loss formula is also derived, allowing a good fit of experimental data over the whole range of. As a result of recent technological advances in fabrication, light can be guided through 1 km of glass fiber with a loss as low as 0. This simple formula considers various bending radii, number of turns, extra bending angle, and wavelength and has. Today, an industry standard exists for measuring optical fiber macrobending, iec 60793147 measurement methods and test procedures macrobending loss. The analysis of the microbending loss shows that the transition component is a maximum at a given correlation length which can be simply expressed in terms of. Curvature and microbending losses in singlemode optical. Theoretical investigations related with the bending of fibers. Calculation of bends losses in singlemode fibers and the critical radius of curvature by two light sources.
View enhanced pdf access article on wiley online library html view download pdf for offline viewing. Influence of curvature on the losses of doubly clad fibers. The expansion coefficients are determined by matching the superposition field to the field of the fiber along a cylindrical surface that is tangential to the outer perimeter of the curved fiber. Calculation of bends losses in singlemode fibers and the critical. In this paper, we present the results of extensive singleradius bend loss measurements for two different fibers over wide ranges of wavelength 8001600 nm and curvature radius. Other layers of a fiber optic cable are used for fiber protection and manufacturing purposes. Investigation of bending loss in a singlemode optical. Contrary to naive intuition, this field deformation may substantially decrease the radiation losses of modes with low mode number. The standard describes the most common approach, wrapping the fiber on a. Curvature loss formulas of optical fibers usually ignore the effect of field deformation caused by the curved axis of the fiber.
The stepindex optical fiber that we use is curved during its manufacturing at a high temperature. The present paper reports the analytical bending loss formula. Fiber bending losses including both macro and microbending losses are important factors for designing low loss optical fibers. D fiber by reducing bending loss in the network as shown in the case below. Bend ing loss is one of the important factors to be consid ered in these applications. Here we shall confine our study of losses by elaborating. R simulation results are compared with formula given in5 5marcuse, dietrich, curvature loss formula for optical bers, josa 66. Theoretical investigations related with the bending of fibers began in the 70s, when dietrich marcuse presented a formula for curvature loss in optical fibers 2. The loss formula for optical fibers with constant radius of curvature of their axes is derived by expressing the field outside of the fiber in terms of a superposition of cylindrical outgoing waves.
Equation 4 is also the key idea that the coefficient of radiation loss depends on the exponential radius curvature. Moreover, reference 5 manipulates with a different type of losses of single mode optical fiber pertaining to different parameters such as wavelength, core radius and curvature of fiber. Optical fiber communication conference optical society of america, 2011, p. Cole abstractthis paper presents an improved curvature loss formula for optical waveguides, which is shown to accurately predict the bend loss of both singlemode and multimode. Macro bending losses in single mode step index fiber science. Besides these, different types of optical interconnects have been proposed to avoid optical bending losses 6, 7, 8. Bend losses are a frequently encountered problem in fiber optics. The formula expands upon a previous formula derived by marcuse, greatly improving its accuracy for the case of multimode fiber. These two components make propagation of light with minimal loss possible. Various theoretical methods exist to predict curvature loss. Abstractthis paper presents an improved curvature loss formula for optical waveguides, which is shown to accurately predict the bend loss of both singlemode and multimode fibers. The bending loss of polarization maintaining optical fiber.
An attenuation of 10 db means that the optical power pl at the end of the fiber is only 10% of the initial power p0. The optical fiber bending loss phenomena is used as a transduction effect in some types of intrinsic optical fiber sensors temperature, displacement, strain 1,2,20. Module 3 attenuation in optical fibers photonic communications engineering i alan e. A 3db attenuation gives 50%, and 1 db is about 80%. Analytical bending loss formula of optical fibers with. A typical attenuation coefficient a against wavelength l is shown in figure 4 for common low loss fused silica fiber. Field deformation and loss caused by curvature of optical. Modeling of bend losses in singlemode optical fibers. Research institute of electrical communication, tohoku university, sendai, japan 980.
The loss formula for optical fibers with constant radius of curvature of their. Simplified formula of bending loss for optical fiber sensors. Simplified formula of bending loss for optical fiber. Based on the principle that the light transmission loss will increase suddenly under big curvature, a fiber optic sensor is proposed to monitor respiratory chest circumference. Citeseerx document details isaac councill, lee giles, pradeep teregowda.
The range of optical loss over which a fiber optic link will operate and meet all specifications. Radiative losses occur whenever an optical fiber undergoes a bend of finite radius of curvature. Curvature of a singlemode optical fibre gives rise to two principal forms of additional transmission loss, namely transition loss and pure bend loss. The electric e and magnetic m fields are perpendicular to each other and to the propagation vector k, as shown below power density is given by poyntings vector, p, the vector product of e and h. Random microscopic bend of the fiber axis that can arise when the fibers are incorporated into cables. Pdf modeling of bend losses in singlemode optical fibers. In the 1980s, harris and peters, presented experimental loss measurements as a function of the wavelength and bending radius 3. We also propose a simplified formula for sensitivity of the fiber optic bending loss in this. The return loss designates the total fractional power. Marcuse, curvature loss formula for optical fibers, j.
Hollowcore conjoinedtube negativecurvature fibre with. They become even more critical for large effective area fibers. Since each single optical fibre in a fiber cable has. Because the fiber is untreated, the sensitivity of this sensor is low and it cannot distinguish the bending direction. Several studies both theoretical and experimental have been carried out to investigate inplane bend losses in single and multimode optical fibers 1, 2. This simple formula considers various bending radii, number of turns, extra bending angle, and wavelength and has good agreement with theoretical and experimental data. Optical fibers installed for ftth applications are bent at the corners of walls, causing severe power loss and affecting the transmission efficiency. Another fiber property that needs to be considered for large effective area fiber designs is the cable cutoff wavelength, above which the fiber can. A simple fiber optic bending loss formula is achieved for optical fiber sensors. Laser and optoelectronics dept by lecturer jassim k. Influence of curvature on the losses of doubly clad fibers, appl. The temperature dependence of the bending loss light energy in multimode optical fibers is reported and analyzed. Bending loss of polarization maintaining optical fiber.
Calculation of bends losses in singlemode fibers and the. Flexible optical waveguide bent loss attenuation effects analysis. Flexible optical waveguide bent loss attenuation effects. Improved bend loss formula verified for optical fiber by simulation and experiment abstract. Optical losses extrinsic fiber losses bending losses. You can easily remember the directions if you curl e into h with the fingers of the right hand. The loss is relative to the transmitter output power. Controlling of optical fiber bending losses through warn. This paper presents an improved curvature loss formula for optical waveguides, which is shown to accurately predict the bend loss of both singlemode and multimode fibers. Studying the effect of curvature in the multimode optical fiber. Improved bend loss formula verified for optical fiber. Bending losses in a radially inhomogeneous profile fiber were studied, taking into account bend. Typically, these losses rise very quickly once a certain critical bend radius is reached.
This paper presents a method for analyzing bending loss formula for the hybrid mode propagating in a uniform bend. Influence of curvature on the losses of doubly clad fibers dietrich marcuse author information. This formula is confirmed in the particular case of a leaky lp 01 mode in a dic fiber with a moderate curvature, by means of combination of the standard analytical perturbation analysis of dic fibers with a ray analysis of the field in the outer cladding. An extension is derived of a bendinglosscoefficient equation derived by marcuse j. As a hybrid mode, we chose the lp mode and found dependency of the bending loss formula on the directional angle, propagation constant and the amplitude ratio and phase difference of the constituent mode. Radiative loss occurs in fibers due to bending of finite radius of curvature in optical fibers. The value of the attenuation factor depends greatly on the fiber material and the manufacturing tolerances, but the figure below shows a typical optical fiber s attenuation spectral distribution. Analytical bending loss formulas are given for arbitrary mode numbers in step. A new curvature loss formula for leaky modes is derived from a direct application of the volume current method. Pdf hollowcore conjoinedtube negativecurvature fibre. Pdf fiber optic bending loss sensor for application on. The typical fused silica glass fibers we use today has a minimum loss at 1550nm. Fiber optics, macro bending, loss, wrapping turn, single mode, multi mode, step. Improved bend loss formula verified for optical fiber by.
The optical performance in term of the return and insertion losses was measured using a loss test set lts3900, exfo, which combines a stable optical source, an optical power meter and an optical return loss meter. Losses of modes with high mode numbers are, however, increased. The method basically consists of measuring the insertion loss of a fiber sample deployed in the specified bend radius. Macroscopic bends having radii that are large compared to the fiber diameter. Hollowcore conjoinedtube negative curvature with ultralow loss. If the radius of the core is large compared to fiber diameter, it may cause large curvature at the position where the fiber cable turns at.