Topic
Mode scrambler
About: Mode scrambler is a research topic. Over the lifetime, 896 publications have been published within this topic receiving 13595 citations.
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Patent•
27 Aug 2009
TL;DR: An optical fiber comprises a first fiber part (F1) provided with a first silica core (1), the cross section of which is formed to be rectangular or square and a first clad (2a) formed so as to clad the first core as discussed by the authors.
Abstract: An optical fiber comprises a first fiber part (F1) provided with a first silica core (1) the cross section of which is formed to be rectangular or square and a first clad (2a) formed so as to clad the first core (1); and a second fiber part (F2) provided with a second silica core (11) the cross section of which is formed to be neither rectangular nor square and a second clad (12) formed so as to clad the second core (11). In order that laser beams having propagated along the first core (1) enters the second core (11), the second fiber part (F2) is subjected to fusion splice to the first fiber part (F1).
2 citations
TL;DR: In this paper, a random diffuser and a spatial light modulator (SLM) are used to reduce modal crosstalk in a mode-division multiplexing (MDM) network.
Abstract: The mode-division multiplexing (MDM) technique enables the transmission of multiple signals within a multi-mode
fiber (MMF) or a few-mode fiber (FMF). To construct an efficient and flexible MDM network in the same way as a
wavelength-division multiplexing network, a mode conversion method with low modal crosstalk is required for
switching between arbitrary spatial modes. However, in general, modal crosstalk is strongly dependent on the intensity
pattern before mode conversion, and it is increased particularly for higher order modes. In order to reduce modal
crosstalk, we propose a method using a random diffuser and a spatial light modulator (SLM). In the proposed method,
firstly, the input spatial mode is dispersed uniformly by the random diffuser. Subsequently, the diffused phase
distribution is canceled and converted into the desired spatial mode by the SLM, which displays phase difference
between desired and diffused modes. Consequently, every spatial mode can be evenly converted into a desired mode.
Here, we numerically simulate and confirm that the proposed method can reduce modal crosstalk compared to the
conversion method without the random diffuser.
2 citations
TL;DR: This work experimentally investigates the applicability of the proposed method for measuring the mode excitation ratio in a two-mode fiber and proposes an alternative formulation to reduce experimental error.
Abstract: In a previous paper, we proposed a simple method for measuring the mode excitation ratio in a two-mode fiber (TMF). Here, we experimentally investigate the applicability of the proposed method and also propose an alternative formulation to reduce experimental error.
2 citations
Patent•
06 Mar 1986
TL;DR: In this article, the difference between projection light from a pinhole when the diameter of the pinhole is (r) and that when (r+DELTAr) while rotatig a turntable, and obtaining a far visual field image was calculated.
Abstract: PURPOSE:To measure transmission characteristics with good reproducibility by calculating the difference between projection light from a pinhole when the diameter of the pinhole is (r) and that when (r+DELTAr) while rotatig a turntable, and obtaining a far visual field image. CONSTITUTION:The calculation of the far visual field image (FEP) of light projected frm an annular fine part 4 of a graded type optical fiber 1 between the radii (r) and (r+DELTAr) of the core 2 is carried out on the basis of the difference between the projection light when the diameter of the pinhole 6 is (r) and that when (r+DELTAr). Then, this is measured and computed while the turntable 7 is rotated successively to obtain FEP11. Then, such a mode scrambler that FEP11 of the annular fine part with constant width is equal is used. Consequently, the reproducibility of measurements of transmission band width and light loss is obtained.
2 citations
TL;DR: In this article, the results of fiber mode scrambler experiments for the Infra-Red Doppler instrument (IRD) on the Subaru 8.2m telescope were reported.
Abstract: We report the results of fiber mode scrambler experiments for the Infra-Red Doppler instrument (IRD) on the Subaru 8.2-m telescope. IRD is a fiber-fed, high precision radial velocity (RV) instrument to search for exoplanets around nearby M dwarfs at near-infrared wavelengths. It is a high-resolution spectrograph with an Echelle grating. The expected RV measurement precision is 1 m s-1 with a state of the art laser frequency comb for the wavelength calibration. In IRD observations, one of the most significant instrumental noise is a change of intensity distribution of multi-mode fiber exit, which degrades RV measurement precision. To stabilize the intensity distribution of fiber exit an introduction of fiber mode scrambler is mandatory. Several kinds of mode scramblers have been suggested in previous research, though it is necessary to determine the most appropriate mode scrambler system for IRD. Thus, we conducted systematic measurements of performance for a variety of mode scramblers, both static and dynamic. We tested various length multi-mode fibers, an octagonal fiber, a double fiber scrambler, and two kinds of dynamic scramblers, and their combinations. We report the performances of these mode scramblers and propose candidate mode scrambler systems for IRD.
2 citations