Many Congratulations to Dr. Majid Haddawi for achieving PHD degree! Many congratulations on your success. You’ve inspired all of us not only to dream but also to work hard to achieve them. Wish you many years of achievement of your goal and success.
Plasmonic heterostructure biosensor based on perovskite/two dimensional materials
Seyedeh Bita Saadatmand, Samad Shokouhi, Seyedeh Mehri Hamidi,
Hamidreza Ahmadi, Maryam Babaei
We propose a bimetallic glucose sensor based on surface plasmon using three-dimensional metal halide perovskites and two-dimensional material. The transfer matrix method and density functional theory corroborated by finite-element simulation are used for numerical analysis for the first time. In the angle interrogation method, MAPbBr3 and monolayer graphene enhanced sensitivity by 254%. A conventional Ag-based sensor has a sensitivity of 113 deg/RIU, whereas the bimetallic/ MAPbBr3/ graphene stack has a sensitivity of 400.25 deg/RIU with 22 nm Ag/ 22 nm Au/ 17 nm MAPbBr3/ graphene. Furthermore, the signal-to-noise ratio, figure of merit, and detection range of the proposed structure are 0.153 deg? 1, 61.23 RIU? 1, and 1.33–1.345, respectively. We also investigate the ductility, temperature stability, thermodynamics, and mechanical stability of metal halide perovskites in detail. The results show that compared to published results, the proposed SPR sensor has significantly improved characteristics.
In these days, the Journal of SSRN 4572475 published a new paper entitled as “Frequency Stabilization Technology of 1560-Nm Fiber Faser Based on Rubidium Modulation Transfer Spectroscopy“
Abstract: The modulation transfer spectroscopy technique used to stabilize two different transition lines of rubidium, required for laser cooling of atoms, is investigated. The 1560-nm fiber laser is adopted as the laser source, to address the weak spectral features of repumping laser, a theoretical study is conducted followed by experimental verification. The 87Rb D2 line F=1 → F’ = 0,1 cross-transition (close to F = 1 → F’= 2 repumping transition) temperature- enhanced MTS signal is observed. The laser linewidth after locking is 35.36 kHz, and the 1-s stabilities of the frequency stabilized cooling laser and repumping laser are 7.13E-12 and 3.48E-11, respectively.
In these days, the journal of Advanced Materials published a new paper entitled as “Toward Plasmonic Neural Probes: SERS Detection of Neurotransmitters through Gold-Nanoislands-Decorated Tapered Optical Fibers with Sub-10 nm Gaps”
Integration of plasmonic nanostructures with fiber-optics-based neural probes enables label-free detection of molecular fingerprints via surface-enhanced Raman spectroscopy (SERS), and it represents a fascinating
technological horizon to investigate brain function. However, developing neu-roplasmonic probes that can interface with deep brain regions with minimal invasiveness while providing the sensitivity to detect biomolecular signatures in a physiological environment is challenging, in particular because the same waveguide must be employed for both delivering excitation light and collecting the resulting scattered photons. Here, a SERS-active neural probe based on a tapered optical fiber (TF) decorated with gold nanoislands (NIs) that can detect neurotransmitters down to the micromolar range is presented. To do this, a novel, nonplanar repeated dewetting technique to fabricate gold NIs with sub-10 nm gaps, uniformly distributed on the wide (square milimeter scale in surface area), highly curved surface of TF is developed. It is experimentally and numerically shown that the amplified broadband near-field enhancement of the high-density NIs layer allows for achieving a limit of detection in aqueous solution of 10−7 m for rhodamine 6G and 10−5 m for sero-tonin and dopamine through SERS at near-infrared wavelengths. The NIs-TF technology is envisioned as a first step toward the unexplored frontier of in vivo label-free plasmonic neural interfaces.
In these days, the Journal of Physical Review Letters published a new paper entitled as “Improved Limits on the Coupling of Ultralight Bosonic Dark Matter to Photons from Optical Atomic Clock Comparisons“
We present improved constraints on the coupling of ultralight bosonic dark matter to photons based on long-term measurements of two optical frequency ratios. In these optical clock comparisons, we relate the frequency of the 2S1=2ðF ¼ 0Þ ↔ 2F7=2 ðF ¼ 3Þ electric-octupole (E3) transition in 171Ybþ to that of the 2S1=2 ðF ¼ 0Þ ↔ 2D3=2 ðF ¼ 2Þ electric-quadrupole (E2) transition of the same ion, and to that of the 1S0 ↔ 3P0 transition in 87Sr. Measurements of the first frequency ratio νE3=νE2 are performed via interleaved interrogation of both transitions in a single ion. The comparison of the single-ion clock based on the E3 transition with a strontium optical lattice clock yields the second frequency ratio νE3=νSr. By constraining oscillations of the fine-structure constant α with these measurement results, we improve existing bounds on the scalar coupling de of ultralight dark matter to photons for dark matter masses in the range of about ð10−24–10−17Þ eV=c2. These results constitute an improvement by more than an order of magnitude over previous investigations for most of this range. We also use the repeated measurements of νE3=νE2 to improve existing limits on a linear temporal drift of α and its coupling to gravity.
