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Fabrication and characterization of high Q polymer micro-ring resonator and its application as a sensitive ultrasonic detector.

Ling T, Chen SL, Guo LJ - Opt Express (2011)

Bottom Line: Quality factors as high as 10(5) have been measured at telecommunication wavelength range.A noise equivalent pressure (NEP) is around 88 Pa over a bandwidth range of 1-75 MHz.We have improved the NEP by a factor of 3 compared to our previous best result.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, USA.

ABSTRACT
Smooth sidewall silicon micro-ring molds have been fabricated using resist reflow and thermal oxidation method. High Q factor polymer micro-ring resonators have been fabricated using these molds. Quality factors as high as 10(5) have been measured at telecommunication wavelength range. By carefully examining the different loss mechanisms in polymer micro-ring, we find that the surface scattering loss can be as low as 0.23 dB/cm, much smaller than the absorption loss of the polystyrene polymer used in our devices. When used as an ultrasound detector such a high Q polymer micro-ring device can achieve an acoustic sensitivity around 36.3 mV/kPa with 240 μW operating power. A noise equivalent pressure (NEP) is around 88 Pa over a bandwidth range of 1-75 MHz. We have improved the NEP by a factor of 3 compared to our previous best result.

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Sidewall SEM image of the polymer micro-ring fabricated from the mold: (a) without resist reflow process, (b) with resist reflow process, (c) with resist reflow and thermal oxidation process.
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g001: Sidewall SEM image of the polymer micro-ring fabricated from the mold: (a) without resist reflow process, (b) with resist reflow process, (c) with resist reflow and thermal oxidation process.

Mentions: The first important step is the PMMA resist reflow, which is applied before the silicon oxide etch step. By choosing a suitable temperature and time duration, this reflow process can greatly reduce imperfections in the PMMA resist patterns and harden the edge of the PMMA resist. Too low of a temperature will not cause the resist to reflow, while too high of a temperature will cause deformation in the coupling gap region, which could significantly increase the optical loss. After a number of experiments, the appropriate PMMA resist reflowing temperature and time duration was determined to be 115°C for 90 seconds. Figure 1Fig. 1


Fabrication and characterization of high Q polymer micro-ring resonator and its application as a sensitive ultrasonic detector.

Ling T, Chen SL, Guo LJ - Opt Express (2011)

Sidewall SEM image of the polymer micro-ring fabricated from the mold: (a) without resist reflow process, (b) with resist reflow process, (c) with resist reflow and thermal oxidation process.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368304&req=5

g001: Sidewall SEM image of the polymer micro-ring fabricated from the mold: (a) without resist reflow process, (b) with resist reflow process, (c) with resist reflow and thermal oxidation process.
Mentions: The first important step is the PMMA resist reflow, which is applied before the silicon oxide etch step. By choosing a suitable temperature and time duration, this reflow process can greatly reduce imperfections in the PMMA resist patterns and harden the edge of the PMMA resist. Too low of a temperature will not cause the resist to reflow, while too high of a temperature will cause deformation in the coupling gap region, which could significantly increase the optical loss. After a number of experiments, the appropriate PMMA resist reflowing temperature and time duration was determined to be 115°C for 90 seconds. Figure 1Fig. 1

Bottom Line: Quality factors as high as 10(5) have been measured at telecommunication wavelength range.A noise equivalent pressure (NEP) is around 88 Pa over a bandwidth range of 1-75 MHz.We have improved the NEP by a factor of 3 compared to our previous best result.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, USA.

ABSTRACT
Smooth sidewall silicon micro-ring molds have been fabricated using resist reflow and thermal oxidation method. High Q factor polymer micro-ring resonators have been fabricated using these molds. Quality factors as high as 10(5) have been measured at telecommunication wavelength range. By carefully examining the different loss mechanisms in polymer micro-ring, we find that the surface scattering loss can be as low as 0.23 dB/cm, much smaller than the absorption loss of the polystyrene polymer used in our devices. When used as an ultrasound detector such a high Q polymer micro-ring device can achieve an acoustic sensitivity around 36.3 mV/kPa with 240 μW operating power. A noise equivalent pressure (NEP) is around 88 Pa over a bandwidth range of 1-75 MHz. We have improved the NEP by a factor of 3 compared to our previous best result.

Show MeSH