Figure - available from: Advanced Optical Materials
This content is subject to copyright. Terms and conditions apply.
Monolithic Spectrometer. a) Schematic of the spectrometer. The spectrometer consists of a single‐nanowire photodiode array. A grating coupler and photonic crystal filter are also proposed to boost PL coupling efficiency. The on‐chip optical path is also illustrated. b) Image and corresponding fluorescent micrograph (left) of a typical nanowire spectrometer, as well as the mapping of the absorption spectrum of the same nanowire (middle). Absorption spectra and normalized photo‐response spectra of six typical constituent photodiodes as marked in the image (right). Scale bar: 6 µm. c) I–V curves of the first photodiode shown in B, illuminated with different intensities of 520 nm laser. d) The saturated photo‐current in (c) as a function of the illumination power. The dashed line guides a linear change.
Source publication
Monolithic spectrometer is exceptionally attractive to enable compact, low‐cost spectroscopy for portable sensing and lab‐on‐a‐chip functionality. Unfortunately, simple down‐scaling of the microspectrometer size to the chip‐scale severely weakens light–matter interactions and degrades the sensor performance to unacceptable level. Unlike other state...
Citations
... After investigated by abundant researches, miniaturization has been an available vision for spectrometers and diverse micro-spectrometers have been developed therewith [4][5][6][7][8]. Recently, a new strategy for miniaturized spectrometers emerges, where original spectra are reconstructed from pre-calibrated information encoded within a group of detectors with individual response characteristics via computational techniques [9][10][11][12][13][14]. Benefiting from more readily available computer processing power and decrease in microprocessor cost, the reconstructive micro-spectrometers have attracted more and more attention all over the world [15]. ...
... With the rapid development of artificial intelligence, diversified algorithms are utilized to reconstruct spectra, such as least-square method, regularization method, deep neural network (DNN), convolutional neural network (CNN), etc. [9][10][11][12][13][14][16][17][18][19][20][21][22][23][24]. Although these algorithms conveniently improve the performance of micro-spectrometers, they perform badly when the original signal collected to be reconstructed is sparse [9]. ...
Taking advantage of broad response range and snap-shot operation mode, reconstructive spectrometers based on integrated frequency-modulation microstructure and computational techniques attract lots of attention. The key problems in reconstruction are sparse samplings related with the limited detectors and generalization ability due to data-driving principle. Here, we demonstrate abstractly a mid-infrared micro-spectrometer covering 2.5–5 μm, which utilizes a grating-integrated lead selenide detector array for sampling and a hierarchal residual convolutional neural network (HRCNN) for reconstructions. Leveraging data augmentation and the powerful feature extraction ability of HRCNN, a spectral resolution of 15 nm is realized. Over one hundred chemicals, including untrained chemicals species tested with an average reconstruction error of ∼1E-4, exhibit the excellent reliability of the micro-spectrometer. The demonstration of the micro-spectrometer promotes the development of the reconstructed strategy.
... Copyright 2020, Nano letter. (f) Schematic of the monolithic spectrometer [65]. Copyright 2020, Advanced Optical Materials. ...
... A 5 nm spectral resolution and 10 13 Jones room-temperature detectivity were exhibited. This presentation has made new progress in high-resolution and sensitive detection in on-chip spectroscopy [65]. In July 2020, Yun et al. demonstrated a design for a single-photon spectrometer using SNSPDs in cascaded photonic crystal (PC) structures (Figure 3g). ...
... Copyright 2020, Nano letter. (f) Schematic of the monolithic spectrometer[65]. Copyright 2020, Advanced Optical Materials. ...
Spectral analysis is an important tool that is widely used in scientific research and industry. Although the performance of benchtop spectrometers is very high, miniaturization and portability are more important indicators in some applications, such as on-site detection and real-time monitoring. Since the 1990s, micro spectrometers have emerged and developed. Meanwhile, with the development of nanotechnology, nanomaterials have been applied in the design of various micro spectrometers in recent years, further reducing the size of the spectrometers. In this paper, we review the research progress of micro spectrometers based on nanomaterials. We also discuss the main limitations and perspectives on micro spectrometers.
... The ultracompact multimode spectrometer in footprint of 63×12 μm 2 (estimated based on simulation) integrates a highly branched waveguide along with an array of coupled graphene photodetectors, which realize simultaneously spectral dis-persing and light fields detecting. In the bandwidth of 1500-1600 nm, the designed spectrometer achieves the single-mode spectral resolution of 7 nm for each mode of TE 1 -TE 4 by Tikhonov regularization optimization 21,37,38 . Besides, the deep learning algorithms are implemented to tackle the strong mode coupling effects in multimode demultiplexing, and the 15 nm resolution of parallel reconstruction for TE 1 -TE 4 is achieved by the single-shot measurement. ...
Miniaturized spectrometers have been widely researched in recent years, but few studies are conducted with on-chip multimode schemes for mode-division multiplexing (MDM) systems. Here we propose an ultracompact mode-division de-multiplexing spectrometer that includes branched waveguide structures and graphene-based photodetectors, which realizes simultaneously spectral dispersing and light fields detecting. In the bandwidth of 1500-1600 nm, the designed spectrometer achieves the single-mode spectral resolution of 7 nm for each mode of TE 1-TE 4 by Tikhonov regularization optimization. Empowered by deep learning algorithms, the 15-nm resolution of parallel reconstruction for TE 1-TE 4 is achieved by a single-shot measurement. Moreover, by stacking the multimode response in TE 1-TE 4 to the single spectra , the 3-nm spectral resolution is realized. This design reveals an effective solution for on-chip MDM spectroscopy, and may find applications in multimode sensing, interconnecting and processing.
... To date, several fabulous concepts have been conceived and realized. The majority of designs rely on the construction of dispersive elements to spit the incident light into different channels and an array of detectors to measure the intensity at each channel [11][12][13]. However, these devices are particularly demanding of strict incident angle and thus high-precision fabrication process. ...
The miniaturization of spectrometers have attracted much attention owning to the demand for portable or in situ spectral analysis in a wide variety of fields, but it is a great challenge to push them into practical applications due to high cost, complicated configuration, and sensitivity to external disturbance. We report on a miniature Fourier transform (FT) spectrometer based on fiber-tip Fizeau interferometer. Hand pulling or any other types of force can be used to drive optical path difference (OPD) scan. Interferences are monitored as a function of time by two photodetectors, one is used to detect the whole interferogram while the other to measure single-wavelength interferogram. In this design, the instantaneous interference intensity as well as OPD can be obtained in an accurate way so that the exact spatial interferogram of the incident spectrum can be worked out. Consequently, the incident spectrum can be retrieved by FT method. A resolution of 7.69 cm⁻¹ in the wavelength range of 1400 nm ∼ 1700 nm is achieved. Experimental results show that the performance of our device is comparable to the commercial benchtop spectrometer. Our device is independent of the complicated fabrication procedures, easy of usage, and cost effective. We envision that the proposed design will inspire a new concept for constructing simple and cheap spectrometers that is well suited for practical applications.
... 8 These devices have a structure in which a photonic material has dispersive properties for light absorption and transmission, such as a plasmonic structure, 9−12 disordered diffractive optics, 13,14 or nanowires. 15,16 These structures are situated near the optical detector, and the detected results are analyzed by considering the dispersive properties of the photonic material to reconstruct the spectrum of the incident light. Since spectroscopy measurements can be completed on a thin device surface that does not require any optical path length, they can significantly reduce the size of spectrometers. ...
... It is our understanding that only two spectrometers have been demonstrated in which the system sizes are of the same order of magnitude as our footprint of 100 × 100 μm 2 . They are based on nanowires 29,30 or disordered photonic structures 31 , and they have a bandwidth per resolution ratio that is similar to the one in our approach. However, owing to wavelength multiplexing, the system must be calibrated with an iterative reconstruction algorithm to deduce the original spectrum. ...
... Furthermore, the implementation of a spectrometer fabricated strictly by 3D printing can be highlighted as a novelty. The measured ratio of bandwidth per resolution of is in a margin similar to those of other spectrometers that have been demonstrated in this size range 29,31 . In the category of direct spectrometers, the microspectrometer presented here is the first of its kind in this size range (see Fig. S1). ...
... Therefore, an array of slightly different spectrometers could be fabricated, with each being optimised for another part of the spectrum. This is a major advantage with regard to spectrometers fabricated using non-classical approaches, such as colloidal quantum dots 27 , photonic crystal slabs 28 , nanowires 29 , and disordered photonic structures 31 . These methods have either a rather small bandwidth or cannot be intrinsically extended to the infrared region. ...
... This increases the complexity of manufacturing and limits miniaturization. Recently, spectral responsivityengineered nanostructure has been demonstrated to integrate both of these functions (13,(95)(96)(97)(98)(99), as shown in Fig. 5, I and J. For example, a computational spectrometer based on a composition-gradient alloyed semiconductor nanowire was proposed, which can be divided into a number of sections (detectors) along the axial direction (13). ...
... In addition, the minimized footprint of the spectrometer reduces the light-matter interaction, which compromises sensitivity. In a follow-up work, a nanowire spectrometer was developed that can operate in a waveguide mode, providing an improved signal-to-noise ratio for such an ultracompact device (96). ...
Miniaturizing spectrometers
Optical spectroscopy is a widely used characterization tool in industrial and research laboratory settings for chemical fingerprinting and analysis. High-end spectrometers are typically benchtop based with bulky optical components, moving parts, and long path lengths, and they can deliver a wealth of information with ultrahigh precision and bandwidth. There is, however, a drive toward miniaturization of spectrometers, in which concepts in nanophotonics are used to control light on much smaller scales. Yang et al. reviewed recent developments in spectrometry systems, including various fabrication approaches of nanophotonics systems and the software that computationally determines the spectra, that strive to shrink their footprint and open up applications in portable spectroscopy.
Science , this issue p. eabe0722
... A novel digital Fourier transform (dFT) on-chip spectrometer exhibits scalability by using digital controlled optically choosing MZI with different OPD with super fine resolution of 25 pm. Based on wavelength multiplexing principle, unlike monochromatic component allowing only a small amount of light transmission, a unique broadband transmission filters was used as light discrimination components to improve the sensitivity and have broad dynamic operation BW, such as PC slabs filter array [20], colloidal semiconductor quantum dots filters array [22], miniature spectrometers as bandgap gradient CdS x Se 1−x single nanowire spectrometer [34,35], silicon nanowire array spectrometer [21,36]. ...
... A monolithic single nanowire miniature spectrometer was realized by Hasan [34] and Wang [35], taking fully advantages of bandgap-graded semiconductor NW. Firstly, bandgap-graded semiconductor nanowire is a promising wavelength selective component for the advanced on-chip spectrometer because of its large and continuously tunable absorption range (from 505 to 710 nm). ...
... (e) Schematic illustration of silicon nanowire microspectrometer, comprising 24 pixels arranged in a circular pattern. (f) Schematic illustration (cross sectional view) of a single pixel[21,34,35]. ...
Miniature spectrometers provide promising potential for on-chip or in situ optical analysis. In recent years there has been significant progress towards reducing the size and improving the performance of these spectrometers. The workhorse is light splitting components. This work has been led primarily by the innovative use of new light analysis strategies and new nanostructured materials with the notable increase in the spectral range and resolution. This review summarizes the latest developments classified as monochromatic, modulated and computational types of miniature spectrometers according to the spectral extraction methods. Particularly, we highlight the recent advances in designing of sophisticated gratings, resonators, interferometers and photonic crystals (PCs), the emerging of novel nanostructured materials and improvement in the computational spectra reconstruction algorithms. We examine the different approaches employed to reduce size and enhance light-matter interaction of the final spectrometers, especially emphasizing the trade-off between various metrics of the spectrometer including device footprint, measurable spectral range, spectral resolution, sensitivity as well as complementary metal oxide semiconductor compatibility. We also examine potential applications of on-chip spectrometers and outlook where further developments are required.
Spectrometers are key instruments in diverse fields, notably in medical and biosensing applications. Recent advancements in nanophotonics and computational techniques have contributed to new spectrometer designs characterized by miniaturization and enhanced performance. This paper presents a comprehensive review of miniaturized computational spectrometers (MCS). We examine major MCS designs based on waveguides, random structures, nanowires, photonic crystals, and more. Additionally, we delve into computational methodologies that facilitate their operation, including compressive sensing and deep learning. We also compare various structural models and highlight their unique features. This review also emphasizes the growing applications of MCS in biosensing and consumer electronics and provides a thoughtful perspective on their future potential. Lastly, we discuss potential avenues for future research and applications.
