Short-wavelength Infrared Research Articles

Ultra-sensitive mid-wavelength-infrared upconversion detector

We have proposed and experimentally demonstrated an efficient ultra-sensitive mid-wavelength-infrared (MWIR) detector using a periodically poled lithium niobate nonlinear crystal and a silicon single-photon counting module. The involved frequency upconversion technique can spectrally convert the MWIR signal photons to the short-wavelength-infrared (SWIR) region. The internal quantum efficiency (QE) of the upconversion detector (UPD) reaches 8.87% at an average pump power of 10.67 W. The noise equivalent power of the UPD is measured as 3.24×10−15W/Hz1/2 at the MWIR wavelength of 4.6μm. In addition, the long-term stability is manifested by at least 12 h of operation with a relative fluctuation in the count rates as low as 0.35%.

Short-Wavelength Infrared Organic Light-Emitting Diodes from A-D-A'-D-A Type Small Molecules with Emission beyond 1100nm.

Short-wavelength infrared (SWIR) organic light-emitting diodes (OLEDs) have attracted great interest due to their potential applications in biological imaging, infrared lighting, optical communication, environmental monitoring, and surveillance. Due to an intrinsic limitation posed by the energy-gap law, achieving high-brightness in SWIR OLEDs remains a challenge. Herein, the study reports the use of novel A-D-A'-D-A type small molecules NTQ and BTQ for high-performance SWIR OLEDs. Benefiting from multiple D-A effect in conjugated skeleton, the small molecules NTQ and BTQ exhibit narrow optical gaps of 1.23 and 1.13eV, respectively. SWIR electroluminescence (EL) emission from OLEDs based on NTQ and BTQ is achieved, with emission peaks at 1140 and 1175nm, respectively. Not only owing to a negligible efficiency roll-off across the full range of applied current density but also the ability to afford a high operation current density of 5200mA cm-2 , the resultant SWIR OLEDs based on NTQ exhibit a maximal radiant exitance of =1.12mW cm-2 . Furthermore, the NTQ-based OLEDs also possess sub-gap turn-on voltage of 0.85V, which is close to the physical limits derived from the generalized Kirchhoff and Planck equation. This work demonstrates that A-D-A'-D-A type small molecules offer significant promise for NIR/SWIR emitting material innovations.

Effect of MIMO scheme on MWIR FSO link & comparison with SWIR wavelength in the presence of different visibility and strong turbulence circumstances

Abstract In this article, the authors analyse the performance of the “multiple input multiple output (MIMO)” technique on a free space optical (FSO) communication link using the mid wavelength infrared (MWIR) and commonly used short wavelength infrared (SWIR) in the presence of various visibility conditions like clear weather, light haze, dense haze, fog, etc., and strong turbulence regime. A 5 km link range has been considered with different diversity MIMO schemes. The performance analysis has been made for both wavelengths in terms of bit error rate (BER) and link outage probability. As the MIMO diversity is increased, the performance has been improved compared to the single input single output (SISO) scheme. In the presence of foggy conditions and higher turbulence strength, the MWIR wavelength works properly, whereas the SWIR wavelength has not worked for the same signal to noise (SNR) ratio and the same link distance.

Modeling selective narrowband light absorption in coaxial InAs-GaAs0.1Sb0.9 nanowires with partial shell segment coverage

Vertical III-V nanowire (NW) arrays are promising candidates for infrared (IR) photodetection applications. Generally, NWs with large diameters are required for efficient absorption in the IR range. However, increasing the NW diameter results in a loss of spectral selectivity and an enhancement in the photodetector dark current. Here, we propose a nanophotonic engineering approach to achieving spectrally-selective light absorption while minimizing the volume of the absorbing medium. Based on simulations performed using rigorous coupled-wave analysis (RCWA) techniques, we demonstrate dramatic tunability of the short-wavelength infrared (SWIR) light absorption properties of InAs NWs with base segments embedded in a reflective backside Au layer and with partial GaAs0.1Sb0.9 shell segment coverage. Use of a backside reflector results in the generation of a delocalized evanescent field around the NW core segment that can be selectively captured by the partially encapsulating GaAs0.1Sb0.9 shell layer. By adjusting the core and shell dimensions, unity absorption can be selectively achieved in the 2 to 3 μm wavelength range. Due to the transparency of the GaAs0.1Sb0.9 shell segments, wavelength-selective absorption occurs only along the InAs core segments where they are partially encapsulated. The design presented in this work paves the path toward spectrally-selective and polarization-dependent NW array-based photodetectors, in which carrier collection efficiencies can be enhanced by positioning active junctions at the predefined locations of the partial shell segments.

Gain and Excess Noise in HgCdTe e-Avalanche Photodiodes at Various Temperatures and Wavelengths

Avalanche photodiodes (APDs) can amplify the weak optical signal as well as enable higher receiver sensitivity due to the internal avalanche gain, but the impact ionization process can also introduce the “excess noise”, which limits the practically achievable signal-to-noise ratio (or sensitivity) and gain-bandwidth product. Hg <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{1} -\textit{x}}$</tex-math> </inline-formula> Cd <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{x}}$</tex-math> </inline-formula> Te electron-initialed APDs (e-APD) have been demonstrated to exhibit high performance in terms of gain and excess noise at 77 K. Here, we discuss the gain and excess noise properties of multiple Hg <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{1}-\textit{x}}$</tex-math> </inline-formula> Cd <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{x}}$</tex-math> </inline-formula> Te e-APDs with different Cd compositions targeting at short-wavelength infrared (SWIR), mid-wavelength infrared (MWIR), and long-wavelength infrared (LWIR) band operating at various temperatures. It demonstrates that the gain of APDs increases as the temperature decreases and the cutoff wavelength of the devices increases, which is related to the decrease of electron effective mass, optical photon scattering rate, and bandgap of the materials. In addition, the low excess noise of less than 1.6 at high gains is also achieved for the devices over a wide range of temperatures. The large spin-orbit splitting energy ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $</tex-math> </inline-formula> so) in comparison to bandgap energy is considered to be responsible for the observed pure electron avalanche and exceptionally low excess noise. This work may provide insight into the low-noise HgCdTe APDs and is beneficial for the future applications of high-temperature operating and high-performance optical receivers.

Improved responsivity and detectivity of LPE HgCdTe short-wavelength infrared photodetector by tuning the composition gradient

This work introduces an effective way to improve the responsivity and detectivity of liquid phase epitaxy (LPE) HgCdTe avalanche focal plane array (FPA) for short-wavelength infrared (SWIR) signal detection by tuning the composition gradient. It is contributed to the Hg-Cd interdiffusion at the HgCdTe/CdZnTe interface during the heat treatment. The Cd composition can be redistributed, which gives different composition (band gap) in the absorption and multiplication regions. The newly designed FPA achieves a 50% improvement in responsivity (gain) and a 30% increase in detectivity over the conventional SWIR FPA (−3 V, 80 K). The newly designed FPA also exhibits a superior performance at 130 K than the conventional FPA at 80 K.

Monolithically Integrated PbS Colloidal Quantum Dot Photodetector Crossbar Array for Short‐Wavelength Infrared Imaging

AbstractMonolithically integrated pixels, with stacked PbS colloidal quantum dot (CQD) photodiodes and organic blocking diodes, are developed as the building block for constructing a short‐wavelength infrared (SWIR) crossbar imaging array. Arising from the back‐to‐back stacked configuration and a favorable energy level alignment, holes are blocked from the photodiode at zero and forward biases, which results in the normally‐OFF behavior of the pixels. Based on such device characteristics, the monolithically integrated pixels can effectively suppress electrical crosstalk under illumination in the crossbar array and consume nearly zero standby power. Furthermore, an 8×8 crossbar imaging array with both high imaging quality and low power consumption is achieved, which features as a high‐performance visible–SWIR imaging sensor.

Nonlinear Absorption and Refraction Properties of V4C3 MXene and its Use for an Ultra‐Broadband Saturable Absorber

AbstractLarge optical nonlinearity at short‐wavelength‐infrared (SWIR) has enabled 2D MXene to be used explosively in ultrafast nonlinear photonics and optoelectronics. Despite the high technological interest in V4C3 MXene in electrochemistry, investigations from a nonlinear photonics perspective have yet to be conducted. Here, the nonlinear optical characteristics of V4C3 MXene at SWIR wavelengths are systemically investigated. First, Z‐scan measurements are performed and the saturated absorption and self‐defocusing properties of V4C3 MXene at both wavelengths of 1560 and 1910 nm are observed. Density functional theory calculation shows metallic characteristics of V4C3 MXene. Based on the saturable absorption properties of V4C3 MXene, a single saturable absorber (SA) operating at both wavelengths of 1560 and 1910 nm is experimentally implemented. Stable mode‐locked pulses of 638 fs pulse duration at 1559.9 nm are produced instantaneously from an erbium‐doped fiber ring cavity using SA. The same SA generates 1.08 ps mode‐locked pulses at 1911.9 nm from the thulium holmium co‐doped fiber ring cavity. This indicates that the operating bandwidth of this realized V4C3 MXene‐based SA could be at least 350 nm. This work strongly suggests that V4C3 MXene can serve as an ultra‐broadband and high‐performance nonlinear optical material platform in the SWIR regions.

Wurtzite InAs Nanocrystals with Short-Wavelength Infrared Emission Synthesized through the Cation Exchange of Cu3As Nanocrystals

Colloidal InAs nanocrystals (NCs) are among the most promising light emitters in the short-wavelength infrared (SWIR) range. These InAs NCs are eligible to crystalize into two distinct phases, i.e., cubic zinc-blende phase and metastable hexagonal wurtzite phase. However, InAs NCs directly produced through molecular precursors unanimously exhibited zinc-blende structure, and the synthesis of their wurtzite counterparts has never been achieved. Herein, we report the first successful synthesis of high-quality wurtzite InAs NCs, which show bright SWIR photoluminescence with a tunable emission peak and high quantum yield of up to ∼37%. This is achieved by the cation exchange of Cu3As NCs with controllable size and morphology, followed by the growth of inorganic passivation layers to eliminate the possible surface trap centers. We further expand the synthesis route to wurtzite ternary InAs0.5P0.5 NCs with quasi-one dimensional confinement, which exhibit polarized SWIR emission, exploring the potential of these anisotropic NCs as efficient polarized light emitters.

Review of Ge(GeSn) and InGaAs Avalanche Diodes Operating in the SWIR Spectral Region.

Among photodetectors, avalanche photodiodes (APDs) have an important place due to their excellent sensitivity to light. APDs transform photons into electrons and then multiply the electrons, leading to an amplified photocurrent. APDs are promising for faint light detection owing to this outstanding advantage, which will boost LiDAR applications. Although Si APDs have already been commercialized, their spectral region is very limited in many applications. Therefore, it is urgently demanded that the spectral region APDs be extended to the short-wavelength infrared (SWIR) region, which means better atmospheric transmission, a lower solar radiation background, a higher laser eye safety threshold, etc. Up until now, both Ge (GeSn) and InGaAs were employed as the SWIR absorbers. The aim of this review article is to provide a full understanding of Ge(GeSn) and InGaAs for PDs, with a focus on APD operation in the SWIR spectral region, which can be integrated onto the Si platform and is potentially compatible with CMOS technology.

DOWNSCALING OF SOIL MOISTURE PRODUCT OF SMAP

Abstract. Soil moisture as a variable parameter of the Earth's surface plays a very important role in many applications such as meteorology, climatology, water resources management and hydrology. Therefore, access to soil surface moisture product with high spatial resolution is very important. Due to the lack of access to soil moisture information with high spatial resolution, the main goal in this article is to downscale the existing soil moisture products and improve their spatial resolution into 1 square kilometer. For this purpose, two methods based on regression and neural network have been used for downscaling the 3 km soil moisture products of SMAP satellite. To this end, other available satellite data and products including various combinations of land surface temperature (LST), normalized difference vegetation index (NDVI), brightness temperature in different polarizations of (TBH and TBV) passive microwave sensor data, digital elevation model (DEM) and short-wavelength infrared (SWIR) data of MODIS and Sentinel 3 have been used. In this study, two regions in the north and south of Iran, Golestan and Fars provinces, have been examined, due to the lack of ground measurements of soil moisture, the SMAP product with the resolution of 1 km which has been already downscaled by exploiting the Sentinel-1 radar data, was used to evaluate the results. The evaluation results in Golestan and Fars provinces showed the correlation coefficient of 0.82 to 0.93 and 0.72 to 0.77, respectively, and the average percentage of absolute error in both regression and neural network methods was less than 21 to 30 and 42 to 46 percent.

Chip-scale short-wavelength infrared InGaAs microspectrometer based on a linear variable optical filter

An extended short-wavelength infrared microspectrometer by monolithic integrarion of a 256 × 1 InGaAs linear array detector with a wedge-shaped Si/SiO2 Fabry-Perot linear variable optical filter.

Experimental realization of short-wavelength infrared half wave retarder fabricated from ZnO single crystal plates

With increasing interest in studying fundamental phenomena at near-infrared (NIR) and short-wavelength infrared (SWIR) frequencies, it is essential to find optical devices which can alter polarization state in the NIR and SWIR radiation range. However, simple optical components such as wave plates capable of generating and controlling polarization sates in the NIR and SWIR radiation are rare. Therefore, our use of channelled spectra of polarized white photons is reported to extract the dispersion of the phase birefringence Δnp(λ) of the 112‾0 and 11‾00 plates of ZnO single crystal acting as multiple order wave plates. The phase birefringence Δnp(λ) of the 112‾0 and 11‾00 ZnO plates was extracted using a calculation procedure named the wavenumber difference method. The correctness of the birefringence data obtained was also confirmed by recalculating the plate thickness using the Jones matrix technique. Furthermore, the birefringence group velocity factor of the 112‾0 and 11‾00 ZnO plates was also extracted from the channelled spectra of polarized white photons using simple method. For both 112‾0 and 11‾00 ZnO plates, a broad spectral full width at half maximum (FWHM) is observed in SWIR region (1100–2500 nm), therefore, 112‾0 and 11‾00 ZnO plates can act as if they are functioning as a zero-order wave plate.

Retina-Inspired Organic Photonic Synapses for Selective Detection of SWIR Light.

Photonic synapses with the dual function of optical signal detection and information processing can simulate human visual system. However, photonic synapses with selective detection of short-wavelength infrared (SWIR) light have never been reported, which can not only broaden the human vision region but also integrate neuromorphic computation and infrared optical communication. Here, organic photonic synapses based on a new donor-acceptor copolymer P1 are fabricated, which exhibit excellent synaptic characteristics with selective detection for SWIR and extremely low energy consumption (2.85 fJ). The working mechanism is rooted in energy level barriers and unbalanced charge transportation. Moreover, these photonic synapses demonstrate excellent performance in multi-signal logic editing, letter imaging and memory with noise reduction function. This contribution provides ideas of constructing selective-response synapses for artificial visual system and neuromorphic computing.

Retina‐Inspired Organic Photonic Synapses for Selective Detection of SWIR Light

AbstractPhotonic synapses with the dual function of optical signal detection and information processing can simulate human visual system. However, photonic synapses with selective detection of short‐wavelength infrared (SWIR) light have never been reported, which can not only broaden the human vision region but also integrate neuromorphic computation and infrared optical communication. Here, organic photonic synapses based on a new donor‐acceptor copolymer P1 are fabricated, which exhibit excellent synaptic characteristics with selective detection for SWIR and extremely low energy consumption (2.85 fJ). The working mechanism is rooted in energy level barriers and unbalanced charge transportation. Moreover, these photonic synapses demonstrate excellent performance in multi‐signal logic editing, letter imaging and memory with noise reduction function. This contribution provides ideas of constructing selective‐response synapses for artificial visual system and neuromorphic computing.

Performance estimation of optical skin probe in short wavelength infrared spectroscopy based on Monte-Carlo simulation

Optical throughput and optical path length are key parameters to obtain high signal to noise ratio and sensor sensitivity for the detection of skin tissue components based on short wavelength infrared (SWIR) spectroscopy. These parameters should be taken into account at the stage of optical system design. We aim to develop a method to estimate the optical efficiency and the effective water path length of a newly designed SWIR spectroscopy skin measurement system using Monte-Carlo photon migration simulation. To estimate the optical efficiency and the effective water path length, we investigated the characteristics of Monte-Carlo photon migration simulation utilizing one layered simple skin model. Simulation of photon transport in skin was conducted for transmission, transflection, and reflection optical configurations in both first overtone (1540 ~ 1820 nm) and combination (2040 ~ 2380 nm) wavelength ranges. Experimental measurement of skin spectrum was done using Fourier transform infrared spectroscopy based system to validate the estimation performance. Overall, the simulated results for optical efficiency and effective water path length are in good agreements with the experimental measurements, which shows the suggested method can be used as a means for the performance estimation and the design optimization of various in-vivo SWIR spectroscopic system.

High-Grade Copper and Gold Deposited During Postpotassic Chlorite-White Mica-Albite Stage in the Far Southeast Porphyry Deposit, Philippines

Abstract Ninety-eight underground diamond holes (~102 km) drilled by Far Southeast Gold Resources Inc. at the Far Southeast porphyry Cu-Au deposit, Philippines, from 2011 to mid-2013, provide a three-dimensional exposure of the deposit between 700- and –750-m elevation, with surface at ~1,400-m elevation. Far Southeast contains an inferred resource of 891.7 million tonnes (Mt) averaging 0.7 g/t Au and 0.5 wt % Cu, equivalent to 19.8 Moz Au and 4.5 Mt Cu. This contribution reports the spatial and temporal distribution of alteration and mineralization at Far Southeast, notably a white-mica–chlorite-albite assemblage that formed after early secondary biotite and before late quartz–white-mica–pyrite alteration and that is associated with the highest copper and gold grades. Alteration assemblages were determined by drill core logging, short-wavelength infrared (SWIR) spectral analysis, petrographic examination, and a quantitative evaluation of materials by scanning electron microscopy (QEMSCAN) study. Alteration is limited around sparse veins or pervasive where vein density is high and the alteration halos coalesce. The alteration and mineralization zones with increasing depth are as follows: (1) the lithocap of quartz-alunite–dominated advanced argillic-silicic alteration that hosts part of the Lepanto high-sulfidation Cu-Au epithermal deposit (mostly above ~700-m elevation), (2) an aluminosilicate-dominated zone with coexisting pyrophyllite-diaspore ± kandite ± alunite and white mica (~700- to ~100-m elevation), (3) porphyry-style assemblages characterized by stockwork veins (below ~500-m elevation), (4) the 1 wt % Cu equivalent ore shell (~400- to –300-m elevation), and (5) an underlying subeconomic zone (about –300- to –750-m elevation, the base of drilling). The ore shells have a typical bell shape centered on a dioritic intrusive complex. The paragenetic sequence of the porphyry deposit includes stage 1 granular gray to white quartz-rich (± anhydrite ± magnetite ± biotite) veins with biotite-magnetite alteration. These were cut by stage 2 lavender-colored euhedral quartz-rich (± anhydrite ± sulfides) veins, with halos of greenish white-mica–chlorite-albite alteration. The white mica is largely illite, with an average 2,203-nm Al-OH wavelength position. The albite may reflect the mafic nature of the diorite magmatism. The quartz veins of this stage are associated with the bulk of copper deposited as chalcopyrite and bornite, as well as gold. Thin Cu sulfide (chalcopyrite, minor bornite) veins with minor quartz and/or anhydrite (paint veins), with or without a white-mica halo, also occur. These veins were followed by stage 3 anhydrite-rich pyrite-quartz veins with white-mica (avg 2,197 nm, illite)–pyrite alteration halos. Combined with previous studies, we conclude that this porphyry system, including the Far Southeast porphyry and Lepanto high-sulfidation Cu-Au deposits, evolved over a period of 0.1–0.2 m.y. Three diorite porphyry stocks were emplaced, and by ~1.4 Ma biotite-magnetite–style alteration formed with quartz-anhydrite veins and deposition of ≤0.5% Cu and ≤0.5 g/t Au (stage 1); coupled with this alteration style, a barren lithocap of residual quartz with quartz-alunite halo plus kandite ± pyrophyllite and/or diaspore formed at shallower depth (&amp;gt;700-m elevation). Subsequently, lavender quartz and anhydrite veins with bornite and chalcopyrite (high-grade stage, avg ~1 wt % Cu and ~1 g/t Au) and white-mica–chlorite-albite halos formed below ~400-m elevation (stage 2). They were accompanied by local pyrite replacement, the formation of hydrothermal breccias and Cu sulfide (paint) veins. Stage 2 was followed at ~1.3 Ma by the formation of igneous breccias largely along the margins of the high-grade zones and stage 3 pyrite-quartz-anhydrite ± chalcopyrite veins with white-mica (mostly illitic) halos. At shallower depths in the transition to the base of the lithocap, cooling led to the formation of aluminosilicate minerals (mainly pyrophyllite ± diaspore ± dickite) with anhydrite plus high-sulfidation-state sulfides and pyrite veinlets. Consistent with previous studies, it is likely that the lithocap-hosted enargite-Au mineralization formed during this later period.

Bright short-wavelength infrared organic light-emitting devices

Organic LEDs that emit light in the short-wavelength infrared (SWIR) region, which spans the 1–2 μm region, are attractive for applications in biosensors, biomedical imaging and spectroscopy, and surveillance. However, fabrication of such devices with high radiance has not yet been achieved owing to an intrinsic limitation imposed by the energy-gap law, which leads to extremely low emission efficiencies. Here, we report that acceptor–donor–acceptor-type molecules with high coplanarity, rigid π-conjugated backbones, an extremely small reorganization energy and an electron–phonon coupling factor are capable of simultaneously providing a strongly suppressed non-radiative recombination rate and a high operation stability at high current density. We achieve electrically driven SWIR organic LEDs with an irradiance of up to 3.9 mW cm−2 (corresponding to 7% of direct sunlight infrared irradiance). These findings should open a wide avenue to a new class of organic SWIR light sources for a broad range of applications.

Investigation of forced flow orientations on the burning behaviours of wooden rods using a synchronised multi-imaging system

The burning behaviour of a wooden rod under various forced flow conditions was investigated by employing a synchronised multi-imaging system integrating visible wavelength, short-wavelength infrared (SWIR), and Schlieren techniques. The wood samples were fixed horizontally and at an inclined angle to study the effect of the surface orientation under forced flow. A small-scale wind tunnel was developed to supply three types of forced flow: concurrent, opposed and cross flow. Each imaging technique helps to gain different physical insights of different aspects of the phenomenon. The combined data provides a comprehensive understanding of the flow effect on fire propagation. It was found that the forced flow strongly influences the often-invisible hot gas flow surrounding the burning rod. The heat feedback from the attached hot flow layer helped to maintain the surface temperature, which further influenced the burning behaviour. The mechanisms that the various flow orientation caused, affected the heated gas differently. Additionally, a method was proposed to monitor the burning process, which used thermal imaging to quantitatively calculate the area of pyrolysis zone on the surface. With the visualisation of the Schlieren images at the critical timings, it was found the thick hot gas flow underneath the wooden rod was a crucial factor that determined the intensity of burning, which may provide important guidance on effective wooden beam fire suppression and control.

A mineralogical and geochemical application for determining hydrothermal alteration zones associated with volcanic-hosted massive sulphide deposits at Tasik Chini area, Peninsular Malaysia

The volcanic-hosted massive sulphide (VHMS) deposits of the Tasik Chini area, Peninsular Malaysia are hosted by Permian felsic volcanic rocks (∼ 290 Ma) of rhyolitic to rhyodacitic composition and comprise two deposits (Bukit Botol and Bukit Ketaya). Although the ores and the felsic volcanic host rocks of these deposits have metamorphosed to greenschist facies and were affected by a complex deformation history, the hydrothermal alteration zones associated with mineralization are preserved and show systematic mineralogical and geochemical changes with increasing proximity to the ore bodies. The geometry of alteration assemblages of the Bukit Botol and Bukit Ketaya deposits shows they occur as semi-conformable or stratabound zones around the ore lenses. According to petrography study and short wavelength infrared (SWIR) spectra measurements supported by X-Ray diffractometer (XRD), the Bukit Botol deposit is characterised by proximal quartz-sericite-pyrite and distal quartz-sericite alteration zones, whereas distal quartz-chlorite-sericite-pyrite-pyrophyllite ± kaolinite and proximal quartz-chlorite-pyrite ± carbonate ± pyrophyllite form the alteration assemblages of the Bukit Ketaya deposit. The geochemical data is coherent with the mineralogical characteristics, using the Ishikawa alteration (AI) and chlorite-carbonate-pyrite (CCPI) indexes, showing the important of chlorite and sericite formation in the ore proximal and ore distal zones. In addition, the molar elemental ratios of Na2O/Al2O3 versus K2O/Al2O3 and MgO/Al2O3 versus K2O/Al2O3 support that the abundance of muscovite (sericite) and chlorite controlled the intensity of alteration at the both deposits. The results of this study indicate that the combination of mineralogy and geochemistry studies help in defining specific alteration styles and related mineral geochemical variations of the VHMS deposits in Tasik Chini area.