Sensor arrays for fast-speed polarimetric imaging rely on the developments of the polarization sensitive photodetectors, of which the absorption efficiency and polarization extinction ratio (PER) are the two major design concerns. This paper presents the numerical results of the design of an efficient superconducting nanowire single photon detector (SNSPD) with high polarization sensitivity by taking advantage of the polarization dependent interferometric effect of a composite mirror. Numerical simulations show that for a SNSPD designed at 1550 nm, the absorption efficiency for parallel polarization is 95% and the PER is 1.5×104. The simulated high PER is in agreement with the value estimated from an analytical model. In order to demonstrate the practicability of the device design, it is also shown that the proposed SNSPD has a good tolerance on fabrication uncertainties. The proposed design of the polarization sensitive SNSPD has a feature that it allows the absorption efficiency and PER to be simultaneously optimized.
Sensor arrays for fast-speed polarimetric imaging rely on the developments of the polarization sensitive photodetectors, of which the absorption efficiency and polarization extinction ratio (PER) are the two major design concerns. This paper presents the numerical results of the design of an efficient superconducting nanowire single photon detector (SNSPD) with high polarization sensitivity by taking advantage of the polarization dependent interferometric effect of a composite mirror. Numerical simulations show that for a SNSPD designed at 1550 nm, the absorption efficiency for parallel polarization is 95% and the PER is 1.5×104. The simulated high PER is in agreement with the value estimated from an analytical model. In order to demonstrate the practicability of the device design, it is also shown that the proposed SNSPD has a good tolerance on fabrication uncertainties. The proposed design of the polarization sensitive SNSPD has a feature that it allows the absorption efficiency and PER to be simultaneously optimized.
We designed a low-filling-factor and polarization-sensitive superconducting nanowire single photon detector (SNSPD), which can achieve a high absorption efficiency and counting rate simultaneously. Numerical simulations show that high absorption efficiency can be achieved by low-filling-factor SNSPDs with a silicon slot and silver reflector. The absorptance of the NbN nanowire for a transverse magnetic (TM) wave at the wavelength of 1550 nm can be 84.4% when the filling factor is only 16.5%, and the corresponding polarization extinction ratio (PER) is 562.9; the absorptance of the NbN nanowire for a transverse electric (TE) wave can be 67.0% when the filling factor is only 11.7%, and the PER is 7.4.
Abstract The multispectral and polarization-sensitive detection of superconducting nanowire single photon detectors (SNSPDs) have been identified in applications, such as quantum information processing and polarimetric imaging systems. Distributed Bragg reflectors (DBRs) demonstrate exceptional wavelength-selective reflectivity, and subwavelength gratings (SWGs) exhibit the ability to separate different polarized light. In this paper, a multispectral and polarization-sensitive SNSPD design is proposed by combining DBRs and SWGs. In the design, the NbN nanowires are positioned on two DBR stacks with respective central wavelengths of 1400 nm and 930 nm, followed by integration of Si-Al composite gratings onto the surface layer. Numerical simulation results show that, setting the fill factor at 0.5, the polarization sensitivity of the SNSPD is ∼0.98, with absorption efficiencies of ∼95%, ∼92%, and ∼94% at wavelengths of 1064 nm, 1310 nm, and 1550 nm, respectively. The design proposed in this work could facilitate the development of high-performance SNSPDs, potentially advancing their applications in multispectral polarization imaging and quantum communication systems.
Superconducting nanowire single photon detector (SNSPD) has been widely used in many fields such as quantum communication due to its extremely high detection efficiency, low dark count rate, high count rate, and low timing jitter. Compared with conventional single-photon detectors with planar structure, SNSPD is typically made a periodical meandering structure consisting of parallel straight nanowires. However, owing to its unique linear structure, the detection efficiency of SNSPD is dependent on the polarization state of incident light, thus limiting SNSPD’s applications in unconventional fiber links or other incoherent light detection. In this paper, a polarization-insensitive SNSPD with high detection efficiency is proposed based on the traditional meandering nanowire structure. A thin silicon film with a high refractive index is introduced as a cladding layer of nanowires to reduce the dielectric mismatch between the nanowire and its surroundings, thereby improving the optical absorption efficiency of nanowires to the transverse-magnetic (TM) polarized incident light. The cladding layer is designed as a sinusoidal-shaped grating structure to minimize the difference in optical absorption efficiency between the transverse electric (TE) polarized incident light and the TM polarized incident light in a wide wavelength range. In addition, the twin-layer nanowire structure and the dielectric mirror are used to improve the optical absorption efficiency of the device. Our simulation results show that with the optimal parameters, the optical absorption efficiency of nanowires to both of the TE polarized incident light and TM polarized incident light has a maximum of over 90% at 1550 nm, and the corresponding polarization extinction ratio is less than 1.22. The fabricated device possesses a maximum detection efficiency of 87% at 1605 nm and a polarization extinction ratio of 1.06. The measured detection efficiency exceeds 50% with a polarization extinction ratio less than 1.2 in a wavelength range from 1505 nm to 1630 nm. This work provides a reference for high-efficiency polarization-insensitive SNSPD in the future.
Polarization sensitive photo-detectors are the key to the implementation of the polarimetric imaging systems, which are proved to have superior performance than their traditional counterparts based on intensity discriminations. In this article, we report the demonstration of a superconducting nanowire single photon detector (SNSPD) of which the response is ultra-sensitive to the polarization state of the incident photons. Measurements carried out on a fabricated SNSPD show that a device efficiency of ~48% can be achieved at 1550 nm for the case of parallel polarization, which is ~420 times larger than that for the case of perpendicular polarization. While the reported polarization ultra-sensitive technique is demonstrated on a single-pixel SNSPD, it is also fully compatible with the multi-pixel SNSPD array platforms that emerged recently.
Abstract Polarization-resolved single-photon detection is a key requirement for advanced quantum photonic applications, including polarization-encoded quantum communication and polarimetric imaging. Although various superconducting nanowire single-photon detector architectures have demonstrated high polarization extinction ratios, concurrently achieving high optical absorption efficiency remains a nontrivial challenge. We propose a compact detector design in which a superconducting nanowire is embedded within a polarization-sensitive silicon grating cavity. The cavity supports distinct longitudinal resonances depending on the incident polarization, thereby enabling selective enhancement of absorption for the desired polarization state. Notably, this configuration introduces minimal fabrication complexity compared to conventional SNSPDs, as the grating cavity can be etched concurrently with the nanowire meander. In numerical simulations, our detector design achieves an absorption efficiency of up to 89.96% and a polarization extinction ratio of 32.39 dB , with a fill factor of just 7%. These results represent a significant advancement toward realizing high-performance, polarization-discriminating single-photon detectors.
Superconducting nanowire single photon detectors (SNSPDs) deliver superior performance over their competitors in the near-infrared regime. However, these detectors have an intrinsic polarization dependence on the incident wave because of their one-dimensional meander structure. In this paper, we propose an approach to eliminate the polarization sensitivity of SNSPDs by using near-field optics to increase the absorption of SNSPDs under transverse magnetic (TM) illumination. In addition, an optical cavity is added to our SNSPD to obtain nearly perfect absorption of the incident wave. Numerical simulations show that the maximum absorption of a designed SNSPD can reach 96% at 1550 nm, and indicate that the absorption difference between transverse electric (TE) and TM polarization is less than 0.5% across a wavelength window of 300 nm. Our work provides the first demonstration of the possibility of designing a polarization-insensitive and highly efficient SNSPD without performing device symmetry improvements.