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Arrayed waveguide grating
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<h2 id="operation-of-awg-devices">Operation of AWG devices</h2> <p>Conventional <a href="/facts/Silica/A3WILp6J">silica</a>-based AWGs, as illustrated in the figure above, are <a href="/facts/Plane_(geometry)/tAUtRFcn">planar</a> lightwave circuits fabricated by depositing layers of <a href="/facts/Doping_(semiconductor)/WrGdtWnm">doped and undoped</a> silica on a <a href="/facts/Wafer_(electronics)/lCBJAoUL">silicon substrate</a>. </p><p>The AWGs consist of a number of input <i>(1)</i> and output <i>(5)</i> couplers, a free space <a href="/facts/Wave_propagation/PXhWIt7k">propagation</a> region <i>(2)</i> and <i>(4)</i> and the grating <a href="/facts/Waveguide/tJS9Y0GH">waveguides</a> <i>(3)</i>. The grating waveguides consists of many waveguides, each having a constant length increment (ΔL). </p> <ul><li>Light is coupled into the device via an optical fiber <i>(1)</i> connected to the input port.</li> <li>Light <a href="/facts/Diffraction/Mk80xXHT">diffracting</a> out of the input waveguide at the coupler/slab interface propagates through the free-space region <i>(2)</i> and illuminates the grating with a <a href="/facts/Normal_distribution/UapjjPyQ">Gaussian distribution</a>.</li> <li>Each wavelength of light coupled to the grating waveguides <i>(3)</i> undergoes a constant change of <a href="/facts/Phase_(waves)/cpGtuVll">phase</a> attributed to the constant length increment in grating waveguides.</li> <li>The diffracted light from each waveguide within the grating undergoes <a href="/facts/Constructive_interference/lI5f78I4">constructive interference</a>, resulting in a <a href="/facts/Focus_(optics)/QuRKfhg6">refocusing</a> of the light at the output waveguides <i>(5).</i> The spatial position of the output channels is wavelength-dependent, determined by the array <a href="/facts/Phase_shift/cpGtuVll">phase shift</a> induced by the constant length increment in the grating waveguides.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Paschotta, Dr Rüdiger. "Arrayed waveguide gratings". RP Photonics AG. Retrieved 2023-06-15. <a href="https://www.rp-photonics.com/arrayed_waveguide_gratings.html" target="_blank">https://www.rp-photonics.com/arrayed_waveguide_gratings.html</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Paschotta, Dr Rüdiger. "Arrayed waveguide gratings". RP Photonics AG. Retrieved 2023-06-15. <a href="https://www.rp-photonics.com/arrayed_waveguide_gratings.html" target="_blank">https://www.rp-photonics.com/arrayed_waveguide_gratings.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Hecht, Jeff (2015). Understanding Fiber Optics. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> </ol>