[Paper Review] Fabrication and Characterization of On-Chip Integrated Silicon Photonic Bragg Grating and Photonic Crystal Cavity Thermometers

Nikolai N. Klimov, Thomas Purdy+1 more|arXiv (Cornell University)|Aug 6, 2015

Photonic and Optical Devices3 citations

TL;DR

This paper presents on-chip silicon photonic thermometers based on Bragg grating and photonic crystal cavity structures, fabricated with a SiO2 cladding layer to enhance sensitivity. The sensors achieve at least eight times higher temperature sensitivity than conventional fiber Bragg grating sensors, demonstrating their viability for high-precision nanoscale temperature sensing.

ABSTRACT

We report on the fabrication and characterization of photonic-based nanothermometers, a silicon photonic Bragg grating and photonic crystal cavity. When cladded with silicon dioxide layer the sensors have at least eight times better sensitivity compared to the sensitivity of conventional fiber Bragg grating sensors. We demonstrate that these photonic thermometers are a viable temperature sensing solution.

Motivation & Objective

• To develop compact, on-chip photonic thermometers for nanoscale temperature sensing.
• To improve temperature sensitivity beyond conventional fiber Bragg grating sensors.
• To integrate Bragg grating and photonic crystal cavity structures on a single silicon chip.
• To characterize the thermal response and sensitivity of the fabricated devices.
• To validate the feasibility of these photonic sensors for practical nanothermometry applications.

Proposed method

• Fabrication of silicon photonic Bragg grating and photonic crystal cavity structures using standard silicon-on-insulator (SOI) platform.
• Application of a thermal oxide (SiO2) cladding layer to enhance the thermo-optic response and sensitivity.
• Use of wavelength shift in the photonic bandgap or reflection peak as a temperature-dependent signal.
• Characterization of the devices under controlled temperature variations to measure sensitivity and linearity.
• Comparison of sensitivity with conventional fiber Bragg grating sensors to evaluate performance improvement.
• Employment of optical interrogation to detect small shifts in resonance wavelength due to temperature-induced refractive index changes.

Experimental results

Research questions

• RQ1 Can on-chip silicon photonic Bragg grating and photonic crystal cavity structures be effectively fabricated for temperature sensing?
• RQ2 How does the SiO2 cladding layer affect the temperature sensitivity of these photonic sensors?
• RQ3 To what extent is the sensitivity of these on-chip sensors improved over conventional fiber Bragg grating sensors?
• RQ4 What is the linearity and reproducibility of the thermal response in these integrated photonic devices?
• RQ5 Can these devices serve as viable alternatives for high-precision nanoscale temperature measurements?

Key findings

• The SiO2-clad photonic thermometers exhibit at least eight times higher sensitivity than conventional fiber Bragg grating sensors.
• The Bragg grating and photonic crystal cavity structures show stable and measurable wavelength shifts in response to temperature changes.
• The integration of both sensor types on a single silicon chip enables compact, scalable temperature sensing platforms.
• The thermal response is linear over the tested temperature range, supporting reliable calibration.
• The use of SiO2 cladding significantly enhances the thermo-optic coefficient, leading to improved sensitivity.
• The devices demonstrate potential for on-chip nanothermometry due to high sensitivity and compatibility with silicon photonics technology.