Author Affiliations
1Center for Advanced Measurement Science, National Institute of Metrology, Beijing 100029, China2School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China3College of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018, China4CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China5CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China6e-mail: panyijie@nim.ac.cn7e-mail: qujf@nim.ac.cnshow less
Fig. 1. Concept of the microcomb-assisted ultra-high-resolution and broad-range WGM photonic thermometer. The sensing element is an on-chip microring WGMR, which generates WGM red shift with increasing temperature (positive thermo-optic coefficient). The PDH locking ensures linewidth reduction and tracking of the WGM. The soliton microcomb provides broadband frequency references, thereby ensuring a broad range. By combining PDH-locking microring with a soliton microcomb, the temperature sensing achieves ultra-high resolution and broad range.
Fig. 2. Beatnote ambiguity during microcomb-assisted temperature sensing. The blue dashed line, red solid line, and green dashed line are the beatnote signals, real temperature curve, and non-ambiguous temperature range (NATR) boundary, respectively.
Fig. 3. (a) SEM image of fabricated Si3N4 microring resonator; (b) image of fabricated MgF2 microdisk resonator; (c) measured transmission spectrum of Si3N4 microring resonator; (d) experimental setup of microcomb-assisted temperature sensing system: AWG, arbitrary waveform generator; ECDL, external-cavity diode laser; EOM, electro-optic modulator; EDFA, erbium-doped fiber amplifier; PD, photodetector; FBG, fiber Bragg grating; PA, preamplifier; RSA, real-time spectrum analyzer; NTC, negative temperature coefficient thermistor; TEC, thermoelectric cooler; Atten., attenuator.
Fig. 4. (a) Optical spectrum of single-soliton microcomb; (b) electrical spectrum of MC-WGM beatnote signal.
Fig. 5. (a) Measured waterfall spectrum shows signal ambiguity near the NATR boundary (white dash line); (b) measured voltage gradient of the feedback signal for ambiguity resolving process; (c) reconstructed temperature curve (blue solid line) and reference temperature curve (red solid line).
Fig. 6. (a) Measured temperature curve shows ultra-high resolution in a broad temperature range, and the temperature deviation curve reflects the heat transfer rate, proving our proposed sensor has a fast response (temp. deviation = meas. temp.−TEC temp.); (b)–(d) mK-level temperature measurement in various temperature regions proves the ultra-high resolution of 136 μK.
Fig. 7. (a) Transmission spectra of two different soliton locking regimes; (b) repetition frequency stability and corresponding temperature stability of two different soliton locking regimes; (c) pump frequency stability and corresponding temperature stability of two different soliton locking regimes.
Material | Structure | Resolution (mK) | Range Limited by FSR (K) | Readout Technique | Reference |
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Silicon | Microring | 10.0 | 280 | Frequency-scanning and peak-searching | [46] | Silicon | Microring | 31.3 | 135 | Frequency-scanning and peak-searching | [7] | Silicon | Microring | 2.90 | 157 | Frequency-scanning and side-of-fringe | [17] | Silica | Microbubble | 40.0 | Not limited by FSRa | Frequency-scanning and optical barcode | [18] | Silicon | Cascaded microrings | 0.09 | Not limited by FSRb | Frequency-locking and reference microring | [40] | Silicon nitride | Microring | 0.058 | Not limited by FSRc | Frequency-locking and microcomb | This work |
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Table 1. Comparison of Chip-Scale Photonic Thermometer Performance