Arrayed Waveguide Gratings | () | Seyringer | Publications | Spie
Download date: Jan. Keywords Arrayed waveguide grating Б Integrated optics devices Б Wave optics. 1 Introduction. The arrayed. The purpose of this paper is twofold. First, a simple but comprehensive and powerful arrayed-waveguide grating (AWG) field model is presented which, based on. Accurate and efficient arrayed waveguide grating simulations for InP membranes (). Open access. Date issued, Access, Open Access. Language.
In such an AWG, the passband i. In many situations it would be more desirable for the AWG to have a flat passband.
USA1 - Arrayed waveguide grating - Google Patents
This is generally because a Gaussian passband requires accurate control over emitted wavelengths, thus making it difficult to use in a system.
This involves creating a double-peaked mode field from the single peak input mode field. When this double-peaked field is convoluted with the single mode output waveguide, the resulting passband takes the form of a single, generally flat peak.
One way of creating the necessary double-peaked field is to use an MMI Multi-Mode Interferometer on the end of the input waveguide or each input waveguide, where there is more than oneadjacent the first slab coupler, as shown in FIG. The MMI creates higher order modes from the single mode input signal and these multiple modes give rise to a double-peaked field at the output of the MMI.
This is described in JP A. The parabolic taper gives rise to continuous mode expansion by excitation of higher order modes of the input signal along the length of the taper, until both the fundamental and second order modes are present, thus forming a double-peaked field at the output end of the taper.
Other non-adiabatic multimode waveguide taper shapes can alternatively be used to achieve the desired passband flattening effect, for example a curvilinear taper shape based on a cosine curve, as described in our pending UK Patent application No. Near-field shaping to produce the desired multiple peak field at the input to the first slab waveguide can also be achieved using other techniques such as a Y-branch coupler, as described in U.
Another technique is the adiabatic mode shaper structure described in our pending UK patent application No. However, when any of the above-described features namely the MMI, parabolic horn, multimode waveguide, Y-branch coupler or other passband flattening structure are employed for the purpose of passband flattening, it is found that AWGs fabricated according to these designs in practice suffer from asymmetry in the passbands of different wavelength output channels.
This is illustrated in FIG. The further the optical signal condenses away from the aiming point C1 of the array waveguides on the output face 20 of the slab waveguide 4, the greater the asymmetry in the passband becomes. One undesirable effect of this asymmetry is that it causes undesirable fluctuation in insertion loss with variation in wavelength of the input optical signal.
This asymmetry effect in the flattened passband is also noted in Published Japanese Patent Application No. However, the given formula does not provide an exact solution i.
According to Marz, the groove function of a Rowland mounting must be linear along the tangent to the grating line of the phasar. As illustrated in FIG.
This is contrary to the teaching of all the well-known papers and patents relating to phasar design, such as the Smit review paper mentioned above and the first patents relating to phasars e. Marz's phasar designs are derived from blazed grating theory, which he has then applied to phasar design. He does not disclose the type of AWG design proposed by Smit and Dragone in which the lateral and angular spacing of the arrayed waveguides on the grating line is constant across the array, as described herein with reference to FIG.
It is an aim of the present invention to avoid or minimize one or more of the foregoing disadvantages. Thus, there is no longer any asymmetry or in practice no significant asymmetry in the AWG channel outputs due to COMA from the second slab waveguide.
Alternatively, the function Arc Sine i. Optical lithography and dry etching then define AWG waveguide structure. We designed various low index AWGs with a typical refrac- 2.
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Design, simulation, evaluation, and technological verification of arrayed waveguide gratings Fig. This function is used to easily adjust calculated geometrical parameters to 1. Number of output waveguides channels: In spite of this fact, this calculation is very 1.
Simulation of channel, GHz, Si3N4-based arrayed waveguide grating applying
Adjacent channel crosstalk between output wave- fast and strongly reduces the time needed for the AWG design. This is because the calculations of the parameters are numeri- cal for more information on these calculations, see Ref.
Another advantage of 3. Uniformity over all the output channels also called the tool is that by changing one parameter one can get prompt nonuniformity: This is very important when optimizing the existing design. The output of the simulations is an AWG spectral response, so called transmission characteris- 1. Number of arrayed waveguides: They are the basis for the calculation of AWG transmis- 2.
These parameters define the performance of AWG and 3. Minimum waveguide separation between wave- also determine its suitability for a particular application. The guides in phased array: This is a very important function allowing As a first step, we created the identical waveguide structure us to calculate the geometrical parameters from the shown in Fig.
Apollo Photonics, Optiwave, and R-Soft. Then, the AWG evident that the simulation performed by Optiwave tool is geometrical parameters output from AWG-Parameters very similar to the measurement. The simulated characteris- tool, see Fig. For all simulations, but they differ from the measured transmission characteris- we used the same calculation conditions.
The output of this evaluation is a set istics are shown in Fig. From these characteristics, it is of transmission parameters describing the optical properties Fig. Design, simulation, evaluation, and technological verification of arrayed waveguide gratings of the designed AWG.
Before we discuss all these parame- parameters. Therefore, the only possibility is to manually ters, let us first describe the functionality of AWG-Analyzer determine these parameters directly out of the transmission tool.
The major problems of the manual acteristics achieved by Optiwave tool. As a consequence of the manual evaluation, the sion parameters must be considered. These parameters are design, simulation, and fabrication of AWGs can become extracted by analyzing AWG transmission characteristics: Besides the men- states, as shown in Fig.
Accurate and efficient arrayed waveguide grating simulations for InP membranes (2015)
While the tioned disadvantages of the manual evaluation, a further measurement method adhered by most AWG vendors is problem is that the evaluation of AWGs is not underlying the deployment of Mueller matrix method,11,12 the way a uniform standard. This means that the definitions of that vendors specify the performance of a device from the AWG transmission parameters, by now, are not standardized. Additionally to this, it is This ends in the fact that without enclosed definitions no one also important to note that the output from all commercially can exactly determine the performance of a present AWG.
To available AWG design tools is the simulated transmission solve these problems, a new software tool was developed. It is divided into three only partially the software-aided calculation of transmission windows Fig.What is AWG Arrayed Waveguide Gratings YouTube
Design, simulation, evaluation, and technological verification of arrayed waveguide gratings 1. Textual representation of raw data: Help for each calculated AWG transmission param- original input file consisting of simulated or measured eter: All transmission parameter calculations bottom left.
Graphical representation of raw data: AWG transmission parameter view: They are listed and explained in Table 1.
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The evalu- ation of the transmission characteristics is performed 3. Recognition of various spectrums: The worst parameter value over all trum transmission characteristics Fig. In the AWG-Analyzer 4. These parameters should correlate with the theoretical trans- of the effective refractive index used in the waveguide struc- mission parameters used in the AWG design. The theoretical ture simulation, in which the calculated value is slightly dif- transmission parameters are the output of the AWG- ferent in each photonic tool.
Further, insertion loss IL Parameters calculation see Fig. As can be seen, there Optiwave and 2. The small deviations is neither insertion loss parameter IL nor nonadjacent chan- result from the slightly different optical signal shapes nel crosstalk parameter nAX nor background crosstalk only.
Measured insertion loss reached 6. This param- parameter BX in this calculation, since these parameters eter is always higher than its simulated value since it also depend mainly on the fabrication process. Here again, only in the Apollo simulation.
This deviation is a result the small deviations result from the slightly different optical Fig. Adjacent channel crosstalk AX, calculated 5. This tool offers one more important func- tical. Adjacent channel crosstalk from Optiwave simulation tion: This difference is a result of the side lobes mation about FSR. This layout was cre- channel band see Fig. In the frequency The simulated transmission characteristics Optiwave tool are domain, this period is called FSR see Fig. The condition presented in Fig.