We present a high-absorption optical stack design for aluminum (Al) kinetic inductance detectors (KIDs). Aluminum can be easily processed in micro-fabrication and is the most conventional superconducting material for KIDs. However, it is challenging to achieve high absorption in the Al absorber because of its high reflection at optical wavelengths. By embedding the thin Al film between an anti-reflection (AR) coating layer and a dielectric-based distributed Bragg reflector, we show that close-to-unity absorption can be achieved around a single wavelength (e.g., ≈98.9% at 1518 nm). The reflection and transmission measurements agree well with the calculation based on the transmission matrix model. We also show our preliminary results of absorption ≥70% in a broader wavelength range (≈230n m) with multilayer AR coatings. The absorber design in a lumped-element KID is discussed. Our work paves the way to high-efficiency photon-counting and energy-resolving Al-based KIDs in the optical to NIR range.

High-absorption Optical Stack for Aluminum Kinetic Inductance Detectors

As a newly developed pair-breaking superconducting detector, microwave kinetic inductance detectors (MKIDs) are simple to integrate in the frequency domain and have already been used in astronomical detection and array imaging at the (sub)millimeter and optical wavelengths. For these applications, the dark noise level of kinetic inductance detectors is one of the key performance indicators. Here we give a detailed introduction to a noise power spectrum analysis method which can perform accurate and effcient noise spectrum analysis in a wide frequency range for kinetic inductance detectors. This method can well balance the noise spectrum resolution and variance performance, by taking the noise data at the resonance frequency with two sampling rates and setting appropriate frequency resolutions for different frequency bands. We use this method to characterize and compare the noise of aluminum (Al) kinetic inductance detectors made from two different micro-fabrication processes. We deposite a 25 nm thick aluminum film on high-resistivity silicon substrate for one device, while place silicon nitride (SiNx) films on both the top and bottom of the aluminum film for another device. It is found that the frequency noise of the device with double silicon nitride films is approximately 25% to 50% of the bare aluminum device. Based on this double silicon nitride film fabrication technique, we further fabricate a few groups of lumped-element aluminum kinetic inductance detectors with various inductor and interdigitated capacitor (IDC) designs. We investigate the noise properties of these devices at different microwave driven powers and bath temperatures, and the experimental results show typical two-level system (TLS) noise behaviors. Our work provides a standard method to characterize the noise power spectrum of kinetic inductor detectors, and also paves the way to develop low-noise aluminum kinetic inductor detectors for terahertz imaging, photon-counting and energyresolving applications.

Noise Spectrum Analysis of Superconducting Kinetic Inductance Detectors

We report measurements characterizing the performance of a kinetic inductance detector array designed for a wavelength of 25 microns and very low optical background level suitable for applications such as a far-infrared instrument on a cryogenically cooled space telescope. In a pulse-counting mode of operation at low optical flux, the detectors can resolve individual 25-micron photons. In an integrating mode, the detectors remain photon noise limited over more than 6 orders of magnitude in absorbed power from 70 zW to 200 fW, with a limiting noise equivalent power of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>4.6</a:mn><a:mo>×</a:mo><a:msup><a:mn>10</a:mn><a:mrow><a:mo>−</a:mo><a:mn>20</a:mn></a:mrow></a:msup><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi mathvariant="normal">W</a:mi><a:mtext> </a:mtext><a:msup><a:mi>Hz</a:mi><a:mrow><a:mo>−</a:mo><a:mn>1</a:mn></a:mrow></a:msup></a:mrow></a:math> at 1 Hz. In addition, the detectors are highly stable with flat power spectra under optical load down to 1 mHz. Operational parameters of the detector are determined including the efficiency of conversion of the incident optical power into quasiparticles in the aluminum absorbing element and the quasiparticle self-recombination constant. Published by the American Physical Society 2024 

A 25-micrometer Single-Photon-Sensitive Kinetic Inductance Detector

We present a new fitting method that can robustly and accurately fit the complex transmission curve of a superconducting resonator in the nonlinear regime. This method takes into account the varying internal current in the resonator at different frequencies and the nonlinear dependence of the inductance on the internal current L=L0(1+I2/I∗2) , where I∗ is a characteristic current. We demonstrate using this method to retrieve important resonator parameters, such as the quality factor and the resonance frequency, from resonators driven below, near, and above bifurcation. We further use this method to retrieve I∗ for lumped-element TiN resonators with various inductor designs. By fitting the resonance frequency shift at different readout powers of each resonator, we can determine the characteristic current I∗ , which is found to be linearly related to the cross-sectional area of the narrow inductor strip. Our method has wide applications in superconducting detector, superconducting qubit and parametric amplifier data analysis where the resonator is driven in the nonlinear regime.

New method for fitting complex resonance curve to study nonlinear superconducting resonators

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Z. Mai

Author Tools

Chat about Author

Papers

New method for fitting complex resonance curve to study nonlinear superconducting resonators