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Ultra-Broadband Add-Drop Filter/Switch Circuit Using Subwavelength Grating Waveguides | IEEE Journals & Magazine | IEEE Xplore

Ultra-Broadband Add-Drop Filter/Switch Circuit Using Subwavelength Grating Waveguides


Abstract:

An ultrabroadband add-drop filter/switch circuit is designed and demonstrated by integrating a pair of subwavelength grating waveguides in a 2 × 2 Mach-Zehnder interferom...Show More

Abstract:

An ultrabroadband add-drop filter/switch circuit is designed and demonstrated by integrating a pair of subwavelength grating waveguides in a 2 × 2 Mach-Zehnder interferometer configuration using silicon photonics technology. The subwavelength grating is designed such that its stopband and passband are distinguished by a band-edge wavelength λedge ~ 1565 nm, separating C and L bands. The stopband (λ <; λedge) is filtered at the drop port of the device, whereas the passband (λ > λedge) is extracted either in cross port or in bar port. The device is designed to operate only in TE polarization. Experimental results exhibit a nearly flat-top band exceeding 40 nm for both stopband and passband. The stopband extinction at cross- and bar ports are measured to be >35 dB with a band-edge roll-off exceeding 70 dB/nm. Wavelength independent directional coupler design and integrated optical microheaters at different locations of the Mach-Zehnder arms for thermo-optic phase detuning are the key for stopband filtering at the drop port and switching of passband between cross- and bar ports with flat top response. Though the insertion loss of fabricated subwavelength grating waveguides are negligibly small, the observed passband insertion loss is ~2 dB, which is mainly due to the combined excess loss of two directional couplers. Experimental results also reveal that the passband switching between cross- and bar ports of the device has been possible with an extinction of >15 dB by an electrical power consumption of Pπ ~ 54 mW. A switching time of 5 μs is estimated by analyzing the transient response of the device. The passband edge could also be detuned thermo-optically at a rate of 22 pm/mW.
Published in: IEEE Journal of Selected Topics in Quantum Electronics ( Volume: 25, Issue: 3, May-June 2019)
Article Sequence Number: 8300111
Date of Publication: 24 May 2018

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