Determination of single-mode fiber coupler design parameters from loss measurements

Leminger, O.; Zengerle, R.

doi:10.1109/jlt.1985.1074259

Cited by 50 publications

(12 citation statements)

References 9 publications

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“…When the part of original cladding is removed to access to the evanescent field and an external variable refractive index material is introduced to replace it, then the guided mode losses may be controlled near the polished region. Analytically derived expressions for the attenuation constants agree with experimentally measured values in such side polished fiber based light attenuation [11,12]. In our case we apply a special LC composite liquid as an external variable refractive index material.…”

Section: Operation Principlesupporting

confidence: 67%

In-fiber variable optical attenuation with ultra-low electrical power consumption

et al. 2005

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The variable optical attenuator (VOA) is an important part of agile optical telecommunication systems. VOAs built on so called free space technologies carry important drawbacks in terms of mechanical reliability, size and optical loss. Evanescent field approach have been used to design VOAs with very low insertion loss. Thermo-optic modulation mechanism was mainly used to control the attenuation level, which unfortunately requires from 10 to 100 times more electrical power compared to above mentioned free space architectures. This power consumption issue may be very challenging in high count arrays of VOAs.At the same time, liquid crystals (LC) have been proved to require very low electrical power for operation.In the present work, we report the creation of evanescent field modulation based VOA with extremely low insertion loss (below 0.1dB) and low electrical power consumption by removing a portion of the original fiber's cladding and replacing it by a specifically synthesized composite LC material, which have an ordinary refractive index lower than the glass one. The initial orientation of LC molecules provides an effective refractive index of the electro-optic cladding that is equal to the refractive index of the original silica cladding. We then create a LC molecule reorientation by the socalled Fredericksz effect by applying to the LC material an electrical voltage. This reorientation changes the refractive index around the depressed cladding area and brings to the partial leakage of the guided radiation into the cladding area, achieving thus attenuation levels above 50dB. Measured maximum electrical power consumption of the VOA is in the microwatt range.

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Section: Operation Principlesupporting

confidence: 67%

In-fiber variable optical attenuation with ultra-low electrical power consumption

et al. 2005

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“…The process of attenuation in side-polished fiber due to guided mode leakage is well understood and described in the literature [13,14]. Existence of an external variable refractive index material in contact with the fibre influences the guided mode and brings a perturbation in its electromagnetic field near the polished region.…”

Section: Operation Principlementioning

confidence: 99%

Low-loss and low-polarization-dependent fiber variable optical attenuators

et al. 2004

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We present the optical performance of a compact variable optical attenuator (VOA) developed at Photintech. The presented VOA's operation principle is based on the guided wave evanescent field manipulation. Access to the evanescent portion of the guided radiation is achieved by replacing the original waveguide's cladding with a thermooptic composite polymer (TOP) material. By changing the temperature of the thermo-optic (TO) material we create guided radiation partial leakage attenuating thus the light. Nevertheless, using polymer materials usually creates significant birefringence due to shrinkage during polymerization or thermal stresses during operation and the polarization dependence of such devices is relatively high. We apply a specific cladding geometry and heating electrode (pending patent of Photintech Inc.), which ensures axial compensation of the birefringence, providing thus very small polarization dependence. In-fiber design provides also low insertion loss (IL) and high dynamic range operation. Control electronics allow the VOA to operate with a precision better than 0.1dB. The developed VOA can be used in agile optical networks, for applications such as dynamic gain equalisation, dynamic channel equalisation, optical transmitter power control and receivers protection in telecommunication systems.

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“…The normalizing factor N 0 of the fundamental mode [1] must be calculated numerically, together with n eff .…”

Section: Principle Of Operation and Theorymentioning

confidence: 99%

Optical Edge Filters Made of Single-Mode Fibers

Zengerle¹,

Leminger²

1985

Journal of Optical Communications

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Optical edge filters with band edges specified between 1.1 μιη and Ι.όμιη were made of bent single-mode fibers in substrate blocks, polished down nearly to the fiber core and covered with immersion liquids. Theoretical and experimental investigations yielded insertion losses below l dB in the transmission bands and attenuations of more than 30 dB in the stop bands. The steepest increase of attenuation at the band edges was 0.6 dB/nm.

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Determination of single-mode fiber coupler design parameters from loss measurements

Cited by 50 publications

References 9 publications

In-fiber variable optical attenuation with ultra-low electrical power consumption

In-fiber variable optical attenuation with ultra-low electrical power consumption

Low-loss and low-polarization-dependent fiber variable optical attenuators

Optical Edge Filters Made of Single-Mode Fibers

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