Molecular cavity optomechanical systems have recently emerged as a promising platform for enhancing infrared detection sensitivity, owing to their ability to up-convert low-frequency infrared (IR) photons to visible frequency range. Generally, under red-detuned pumping in such systems, the ideal conversion efficiency of the IR signal approaches 1. To overcome this efficiency constraint, we propose a scheme that incorporates gain into the infrared cavity of a molecular cavity optomechanical system comprising two cavities and an ensemble of N molecules. The upconversion process, which relies on IR absorption and Raman scattering associated with specific vibrational modes, is significantly amplified by the incorporation of gain under the red-detuned conditions. Moreover, our analysis demonstrates that the added noise is maintained near 0.5.
Molecular cavity optomechanical systems have recently emerged as a promising platform for enhancing infrared detection sensitivity, owing to their ability to up-convert low-frequency infrared (IR) photons to visible frequency range. Generally, under red-detuned pumping in such systems, the ideal conversion efficiency of the IR signal approaches 1. To overcome this efficiency constraint, we propose a scheme that incorporates gain into the infrared cavity of a molecular cavity optomechanical system comprising two cavities and an ensemble of N molecules. The upconversion process, which relies on IR absorption and Raman scattering associated with specific vibrational modes, is significantly amplified by the incorporation of gain under the red-detuned conditions. Moreover, our analysis demonstrates that the added noise is maintained near 0.5.
Molecular optomechanical cavities have recently emerged as a promising platform for frequency upconversion, enabling the quantum coherent conversion of infrared signal into the visible range. In a recent work [F. Zou et al., Phys. Rev. Lett. 132, 153602 (2024)], we proposed an amplification mechanism that can enhance the intensity of the upconverted infrared signals by a factor of 1000 or more within such a cavity under the ideal case without any noise. In this work, we employ the power spectrum method to investigate the noise added to the upconverted signal in a molecular optomechanical cavity along with the conversion efficiency from infrared signal into visible range. In the red-detuned regime, the anti-Stokes sideband achieves superior conversion efficiency relative to the Stokes sideband. Conversely, the Stokes sideband dominates under the blue-detuned condition, which amplifies the infrared signal. We further demonstrate the dependence of the added noise on the coupling strength and decay rates of the system. In particular, we find that when the infrared signal is amplified, the added noise approaches the quantum limit of one quantum.
We propose and demonstrate a high efficiency broadband near infrared single-photon upconversion and detection with a broadband pump laser based on sum frequency conversion in the PPLN crystal. By using a pump laser centered at 1040 nm with a spectral bandwidth of 10 nm, the signal single-photons centered at 1562 nm with a broadband bandwidth up to 7.2 nm are frequency-converted from the near infrared to the visible regime. A maximum conversion efficiency of 18.8% is achieved, while the background noise is measured to be only 1.2 × 10−3 counts/pulse. The corresponding spectral linewidth of the upconverted photons is 0.2 nm. This scheme of broadband infrared single-photon upconversion and detection provides potential solutions in infrared laser ranging, broadband infrared imaging and quantum key distribution.
High-gain amplifiers of electromagnetic signals operating near the quantum limit are crucial for quantum information systems and ultrasensitive quantum measurements.However, the existing techniques have a limited gain-bandwidth product and only operate with weak input signals.Here, we demonstrate a two-port optomechanical scheme for amplification and routing of microwave signals, a system that simultaneously performs high-gain amplification and frequency conversion in the quantum regime.Our amplifier, implemented in a two-cavity microwave optomechanical device, shows 41 dB of gain and has a high dynamic range, handling input signals up to 10 13 photons per second, 3 orders of magnitude more than corresponding Josephson parametric amplifiers.We show that although the active medium, the mechanical resonator, is at a high temperature far from the quantum limit, only 4.6 quanta of noise is added to the input signal.Our method can be readily applied to a wide variety of optomechanical systems, including hybrid optical-microwave systems, creating a universal hub for signals at the quantum level.
Mid-infrared (MIR) imaging plays a pivotal role in chemical sensing, biomedicine, and material analysis, yet its further development is fundamentally constrained by limited room-temperature sensitivity and the lack of efficient multidimensional light-field control. In recent years, frequency upconversion imaging has emerged as a rapidly advancing approach that translates MIR signals to the visible or near-infrared domain, enabling high-sensitivity detection with mature, low-noise photonic platforms. More importantly, by engineering the pump field in nonlinear frequency conversion processes, a multidimensional imaging framework has been established, enabling indirect, all-optical encoding and retrieval of multiple degrees of freedom—including amplitude, phase, spectrum, time, and polarization—of MIR light fields. This paradigm shifts complex light-field manipulation from the MIR to technologically mature short-wavelength regimes, overcoming intrinsic limitations of conventional approaches. In this review, we systematically summarize the principles, architectures, and representative methodologies of MIR upconversion multidimensional imaging, and outline future directions toward high-sensitivity, high-dimensional, and integrated imaging systems, with implications extending to broader photonic and information processing domains.
Single-photon frequency upconversion is a nonlinear process where the frequency of the signal photon is translated to the higher frequency with the complete preservation of all the quantum characteristics of the “flying” qubits [1,2]. One promising application of the singlephoton frequency upconversion is converting the infrared photons to the desired spectral regime (usually visible regime) where the high performance detectors are available for sensitive detections [3-6]. The infrared single-photon frequency upconversion detection technique has been successfully used in a variety of applications, including infrared imaging [7] and infrared ultra-sensitive spectroscopy [8,9]. Additionally, such upconversion detector has greatly benefited the applications stringently requiring efficient photon detection in optical quantum computation and communication [10-12]. Furthermore, due to the phase-matching requirement in the frequency upconversion process, the upconversion detectors have some unique features, such as narrow-band wavelength acceptance [13] and polarization sensitivity [14], both of which render them very useful for fiber based quantum systems [15]. In the recent decade, experiments bear that the photon correlation, entanglement, and photon statistics are all well preserved in the coherent frequency upconversion [16-18].
We demonstrate an efficient mid-infrared single-photon detection system with ultra-low background counts based on the frequency upconversion detection technique. The signal photons of 3.39 μm came from a He–Ne laser and the pump beam was provided by a mode-locked ytterbium-doped fiber laser. Taking into account the pulsed pumping and continuous-wave signaling scheme, the peak conversion efficiency of 64% was achieved at an average pump power of 28.3 mW. The corresponding detection efficiency was inferred to be 6.1% with ultra-low background counts of 400 s −1 .