CIAN IAB Lecture Series – Soha Namnabat

Athermal Silicon Photonic Devices

Date:  Monday, November 30, 2015
Time:  2pm Mountain Time, 1pm Pacific Time, 4pm Eastern Time
Location: University of Arizona, OSC 821 Conference Room

This presentation will also be accessible online. Register to join by clicking on the following link:


Soha Namnabat
Ph.D. Candidate
University of Arizona

Soha Namnabat is a Ph.D. candidate working at the College of Optical Sciences, University of Arizona. Under Prof. Robert Norwood’s supervision, his interest in optical materials and photonic devices lead to conduct research on magneto-optic, electro-optic, and organic polymers as well their application in photonic devices.


The high thermal sensitivity of silicon photonic devices requires them to operate at fixed temperatures in order to avoid cross talk and optical performance degradation.  Heaters or thermoelectric coolers, which are typically used to control the temperature, consume lots of power, which is not acceptable in emerging data center environments.  In order to compensate for thermal drift, improve robustness and reduce power consumption, we are developing a suite of cladding materials with negative thermo-optic coefficients which can be used to offset silicon’s positive thermo-optic coefficient and thereby achieve athermality with little or no active temperature control required.  Previously polymers and titanium dioxide have been used to athermalize silicon ring resonators, but evaporated materials such as titanium dioxide have relatively high cost while polymers that have been demonstrated often can’t survive the relatively high temperatures of backend silicon processing.  We are developing sol-gel materials as an alternative solution, since they have the benefits of simple wet processing (i.e. spin coating), a wide range of potential refractive indices (1.4 to 2.1), and superior high temperature performance compared to typical optical polymers.  We will discuss our design, fabrication and testing of athermal silicon ring resonators using sol-gel claddings as well as approaches for further improving the performance.

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