Experimental investigation of the modulation phase-shift method for the measure of the chromatic dispersion in a single-mode fiber coiled on a covered spool

Abstract

pler is related to the coupling coefficient. The size reduction ratios against minimum line width with different parameters are shown in Figures 1 and 2. SIMULATED AND MEASURED RESULTSTo validate the proposed procedure, a miniaturized 6-dB ring coupler operated at 1 GHz is fabricated and measured. The substrate is FR4 with r ϭ 4.2 and h ϭ 1.6 mm. If the minimum line width is 0.2 mm, the maximum impedance will be 148.67⍀, leading to the minimum size reduction ratio of 0.28. Figure 3 shows the layout of the original 6-dB ring coupler and the reduced version with 12 open stubs. It is noted that the line widths of the original ring coupler are different so as to control the coupling coefficient. In contrast, the line widths of the reduced ring coupler on the circumference are all equal to 0.2 mm, the minimum line width. Figure 4 shows the photograph of the manufactured reduced ring coupler. The frequency responses of these two ring couplers, simulated using Ansoft Serenade, are compared with the results measured by using Agilent 8720ES in Figure 5. In this figure, the discontinuity effects, including T-junction and open end, are considered and compensated. Good agreement between the simulated and measured results at the operation frequency is found, with the exception of the return loss, because it is sensitive to line width and the minimum line width is influenced severely by the manufacturing precision. CONCLUSIONThe size-reduction limit of a ring coupler with restricted minimum line width that is miniaturized by connecting multiple open stubs is derived. The limits of size-reduction ratios of different parameters have been checked. According to the predicted minimum size, a reduced ring coupler has been designed and fabricated in order to validate the proposed procedure. ABSTRACT: The measure of the chromatic dispersion of the optic fibers used in telecommunications networks and high-speed systems is very useful because it permits chromatic-dispersion compensators to be conceived across the wavelength range of interest. The modulationphase-shift method is used to measure chromatic dispersion in a standard single-mode fiber for telecommunication between 1200 and 1600 nm, by measuring the variation of the modulation phase of the transmitted signal modulated by a radio frequency signal, relative to the transmitted signal in a short reference fiber, modulated by the same signal. We verify the reduction of the thermal transitions in the measurement setup and fiber under test, while covering the spool of the fiber.

Frequency domain technique for reducing chromatic dispersion

“…Kaiser Window is used in this research to smooth the signal. Kaiser window which helps to detect the required stream from long stream of bits by changing the center lobe width and sided lobe as in (4).…”

Single-arm three-wave interferometer for measuring dispersion of short lengths of fiber

“…Next, we examine the wavelength spacing between   and   . From (5), ignoring the 3 rdorder term and applying (6), we get,…”

“…Due to its higher precision, MPS has become the industry standard method for measuring dispersion in optical fibers. However, MPS is expensive to implement and its precision is limited by both the stability and the jitter in the RF signal [5]. Moreover, both the TOF and the MPS techniques require long lengths of fiber, from several tens of meters to several kilometers.…”

C-band optical fibers chromatic dispersion measurement at CENAM

“…1 One of the most commonly used methods for chromatic dispersion measurement is the phase shift method, where sinusoidally modulated optical signals at different wavelengths are measured in phase shift after travelling through the fiber, thus allowing to obtain a group delay determination. [2][3][4] In this work we present the first phase-shift technique realization at the Centro Nacional de Metrología of Mexico, devoted to the calibration and measurement capabilities establishment for chromatic dispersion in mono-mode optical fibers. The obtained zero dispersion wavelength showed a good agreement with the previously tested optical fiber certified value.…”