Patent•
Method for designing fiber Bragg grating with arbitrary optical power distribution
01 May 2013-
TL;DR: In this paper, a method for designing a fiber Bragg grating with arbitrary optical power distribution is presented, and a refractive index modulation function of the grating is reconstructed.
Abstract: The invention discloses a method for designing a fiber Bragg grating with arbitrary optical power distribution. A refractive index modulation function of the fiber Bragg grating is reconstructed. The fiber Bragg grating is sectionally processed from given optical power distribution along the length of the fiber Bragg grating, and the amplitudes of a forward transmission mode and a backward transmission mode in the fiber Bragg grating at a resonant wavelength are deduced by combining boundary conditions (uN=1 and v0=0) of the fiber Bragg grating and a law of conservation of energy. Meanwhile, constant phases of the forward transmission mode and the backward transmission mode at the resonant wavelength are deduced for a uniform/apodized fiber Bragg grating according to a transmission matrix method. A reflection coefficient and a coupling coefficient are calculated by using a coupled mode matrix on the basis of the obtained amplitudes and the obtained phases of the forward transmission mode and the backward transmission mode, and the refractive index modulation function of the fiber Bragg grating is deduced from the reflection coefficient and the coupling coefficient to finish the reconstruction design of the fiber Bragg grating. The method is applied to the design of the fiber Bragg grating, and is also applied to the design of the uniform/apodized fiber Bragg grating with the arbitrary optical power distribution.
Citations
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Patent•
12 Feb 2014
TL;DR: In this paper, an RZ to NRZ code type converting fiber bragg grating designing method and a device thereof is presented, where the method comprises the steps of giving a group of group of pseudo-random codes at will, determining the duty ratio and the signal rate, carrying out fast fourier transform on a discretization number value sequence of RZ codes and a discreization number values sequence of NRZ codes to obtain discretisation number value sequences of power spectrums of the RZ code and the NRZ Code.
Abstract: The invention discloses an RZ to NRZ code type converting fiber bragg grating designing method and a device thereof. The method comprises the steps of giving a group of group of pseudo-random codes at will, determining the duty ratio and the signal rate, carrying out fast fourier transform on a discretization number value sequence of RZ codes and a discretization number value sequence of NRZ codes to obtain discretization number value sequences of power spectrums of the RZ codes and the NRZ codes, using the discretization number value sequence of the power spectrums of the NRZ codes to subtract the discretization number value sequence of the power spectrums of the RZ codes to obtain a group of new discretization number value sequences, choosing a cutting window with the width smaller than the width of one step sideband of the power spectrums of the RZ codes to cut a new discretization number value sequence according to the width of one step sideband of the power spectrums of the RZ codes, obtaining spectrum response of a fiber bragg grating by enabling the new discretization number value sequence to be multiplied with two, and utilizing a sampling grating method or a reversed layer peeling method to design a grating structure according to the spectrum response of the fiber bragg grating. The device can achieves all-optical code type conversion from RZ to NRZ and has the advantages of being simple in structure, high in cost performance, capable of being connected with an optical fiber communicating system easily and the like.
1 citations
Patent•
12 Jun 2020
TL;DR: In this paper, a waveguide grating coupler with high coupling efficiency was designed based on a silicon-on-insulator (SOI) platform, which achieved a coupling efficiency of 83.2% near the wavelength of 1580 nm.
Abstract: The invention discloses a design method of an M-type waveguide grating coupler with high coupling efficiency and belongs to the field of integrated optoelectronics, the method is based on a silicon-on-insulator (SOI) platform. Firstly, a waveguide grating model is designed, then, a nonlinear constraint optimization algorithm waveguide grating model is used and the traditional periodic waveguide grating structure with the optimal average coupling efficiency on the wavelength of 1500 nm to 1600 nm is obtained; innovative research and design are carried out, a novel M-type waveguide grating structure is designed on the basis of a traditional periodic grating structure, the M-type waveguide grating structure is further optimized through several sets of data simulation, the vertical grating coupler with high coupling efficiency is finally obtained, and the high coupling efficiency of 83.2% is achieved near the wavelength of 1580 nm. The waveguide grating coupler design method provided by the invention is high in coupling efficiency and wide in application prospect, has great potential under the condition of using a mature manufacturing process, and can be designed and realized.
Patent•
26 Jan 2018
TL;DR: In this paper, a method for designing a waveguide grating coupler was proposed, in which a function, an input requirement, an output requirement, and a functional structure region of a device are determined and grid division is carried out on a device carrier to form a plurality of pixel bar regions.
Abstract: The invention provides a method for designing a waveguide grating coupler. The method comprises: a function, an input requirement, an output requirement, and a functional structure region of a deviceare determined and grid division is carried out on a device carrier to form a plurality of pixel bar regions; the structure after grid division of the device carrier is initialized before iteration; an optimization condition of iteration is determined; iteration of structures of all pixel bars on the device carrier is carried out successively, wherein the structures of the pixel bars are searchedbased on grid division during each iteration process, each iteration result is calculated by a finite different time domain method, determination is carried out by using the optimization condition ofiteration, the structure is updated during the iteration process if the searched structure enables the performance parameter to be improved, and otherwise, the structure during the iteration does notchange. On the basis of the automatic and simple reversal design method, the design cycle is reduced; the design manpower cost is lowered; and the design freedom degree is increased.
References
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TL;DR: It is found that the discrete layer-peeling algorithm is significantly faster and can be more stable than its continuous counterpart, whereas the continuous algorithm offers some advantages in flexibility.
Abstract: Two methods for grating synthesis which have appeared in the literature recently are compared directly. In particular, we point out the similarity between the two; both algorithms are based on propagation of the fields through the structure with simultaneous evaluation of the coupling coefficient according to simple causality arguments (layer-peeling algorithms). The first published method (the discrete layer-peeling algorithm) is reformulated in a simpler, more efficient way, and it is shown that its implementation can be made exact. For mathematical comparison, a derivation of the second method (the continuous layer-peeling algorithm) is presented. The methods are compared both mathematically and numerically. We find that the discrete layer-peeling algorithm is significantly faster and can be more stable than its continuous counterpart, whereas the continuous algorithm offers some advantages in flexibility.
394 citations
TL;DR: In this article, a differential layer-peeling algorithm is proposed for the design of complex fiber Bragg gratings, which relies on the synthesis of the impulse response of the grating by means of a differential-layer peeling algorithm.
Abstract: Presents an efficient method for the design of complex fiber Bragg gratings. The method relies on the synthesis of the impulse response of the grating by means of a differential layer-peeling algorithm. The algorithm developed takes into account all the multiple reflections inside the grating, giving an exact solution to the inverse scattering problem. Its low algorithmic complexity enables the synthesis of long fiber gratings. The method is illustrated by designing several filters with interest for optical fiber communication systems: dispersionless bandpass filters and second- and third order dispersion compensators.
362 citations
TL;DR: In this paper, a multichannel fiber Bragg grating (FBG) design based on a discrete layer-peeling method is described, which enables us to design any kind of multichannels FBG in which the spectrum responses of the channels can be either identical or non-identical.
Abstract: A multichannel fiber Bragg grating (FBG) design based on a discrete layer-peeling method is described. This novel method enables us to design any kind of multichannel FBG in which the spectrum responses of the channels can be either identical or nonidentical. In particular, a nine-channel dispersion-free FBG and a nine-channel nonlinearly chirped FBG used simultaneously as chromatic dispersion and dispersion slope compensators are described. Unlike the general multichannel FBG designed by a sampling method, these two gratings have ideal flat-topped profiles in both the transmission and the reflection spectra. By optimally detuning the relative phases for the multiple-spectrum channels with an iterative layer-peeling method, we can make maximum use of length-limited photosensitive fiber. Moreover, we show numerically that one can reduce or eliminate the oscillation that inherently exists in the index-change envelope of our multichannel FBG by accepting a decreased extinction ratio of the in-band signal to the out-of-band noises.
35 citations
Patent•
10 Nov 2010
TL;DR: In this paper, an inner wall melt-embedded type multicore single mode polarization-maintaining fiber grating and a manufacturing method are presented. And the fiber core of the multicore fiber core is prepared into the inner wall Melt-Embedded type multi-core single-mode polarization maintaining fiber by an ultraviolet light source through a phase position maskplate writing technology.
Abstract: The invention provides an inner wall melt-embedded type multicore single mode polarization-maintaining fiber grating and a manufacture method. The inner wall melt-embedded type multicore single mode polarization-maintaining fiber grating comprises a multicore fiber, the center of the multicore fiber is an air hole, part of each fiber core of the multicore fiber is embedded in a cladding with the refractive index lower than that of the fiber core while the other part thereof is suspended in the air hole to form an inner wall melt-embedded type multicore single mode polarization-maintaining fiber core in an ellipsoid-like shape, and the fiber core is prepared into the inner wall melt-embedded type multicore single mode polarization-maintaining fiber grating by an ultraviolet light source through a phase position maskplate writing technology. Due to good polarization-maintenance performance of the inner wall melt-embedded type multicore single mode polarization-maintaining fiber designed by the invention, the manufactured multiple polarization-maintaining fiber gratings are integrated into one optical fiber, thus improving integration of optical devices in optical fibers and facilitating simultaneous measurement of multiple physical quantities.
10 citations
Patent•
28 Mar 2007
TL;DR: In this paper, a sampling optical fiber grating preparing method has been described, in which the controlling device which the sampling period changes with the altitude direction of the swing mask plate and the duty cycle doesn't change, keeps the relative altitude of the sampling swing mask and the optical fiber in the process.
Abstract: A sampling optical fiber grating preparing method has the character: the controlling device which the sampling period changes with the altitude direction of the swing mask plate and the duty cycle doesn't change or the duty cycle changes with the altitude direction of the swing mask plate or the sampling periodicity doesn't change, keeps the relative altitude of the sampling swing mask plate and the optical fiber in the process, so it can make the sampling optical fiber grating of different sampling period or the duty cycle by adjusting the relative altitude, also it can make the sampling optical fiber grating of sampling period or the duty cycle changing with the optical fiber axis. So it can decrease the cost and make the complex sampling optical fiber grating.
3 citations