- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
A Preamplifier for a CdHgTe Photodetector
摘要： A preamplifier for operation with an HgCdTe-based nitrogen-cooled IR photodetector (600 nm–15 μ m) is described. The preamplifier operates in the photoconductivity mode. The use of modern microcircuits made it possible to increase the bandwidth of the response to 2 MHz at a noise level of 0.5 nV/Hz1/2, which is close to the fundamental limit that is specified by the resistance of the photosensitive element. The preamplifier was used in an aperture-free scanning near-field optical microscope.
关键词： HgCdTe,IR photodetector,scanning near-field optical microscope,photoconductivity,preamplifier
更新于2025-09-23 15:19:57
-
Active control of chiral optical near fields on a single metal nanorod
摘要： Chiral optical fields (typified by circularly polarized light) localized on the nanoscale enhance the chiral light-matter interaction, which may provide novel potential applications. This property enables the development of an ultrasensitive method for characterization of chiral molecules and nanoscale magnetic control realized by an all-optical method to interconnect spintronic nano-optical devices. A local chiral light source with switchable handedness or controllable chirality is indispensable for building such applications for practical use. In the current major method used for local chiral light generation, the handedness of the light is controlled by the handedness of the nanomaterial, which is not convenient when we need to change the handedness of the light. We experimentally achieve here generation and active control of a highly chiral local optical field by using a combination of an achiral gold nanorod and achiral linearly polarized optical field. By tilting the azimuth angle for the incident linear polarization relative to the axis of the nanorod, either left- or right-handed circularly polarized local optical fields can be generated. Our work may give us a chance to pioneer analytical applications of chiral optical fields and novel spintronic nano-optical devices.
关键词： near-field optics,chiral plasmonics,scanning near-field optical microscope,nanomaterial,polarimetry
更新于2025-09-19 17:15:36
-
Unrevealing Charge Carrier Selective Layer in Silicon Heterojunction Solar Cells via Multifunctional Atomic Force Probes
摘要： The current silicon solar cell with a record efficiency is based on heterojunction contacts that offer carrier selectivity as well as surface passivation simultaneously. One remaining challenge with heterocontacts is the balance between carrier extraction and surface passivation. Here, it is demonstrated that the heterojunction of n-type silicon (N–Si) with the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) removes this trade-off, utilizing the strong depletion of PEDOT:PSS to realize the excellent carrier selectivity. The near-field optical contrast and surface potential distributions of the PEDOT:PSS/N–Si heterojunction via multifunctional atomic force probes are mapped for the first time. Interestingly, a low dielectric value region is observed in N–Si by using scattering-type scanning near-field optical microscopy on the junction cross-section. A special PEDOT:PSS slope is further fabricated to characterize the dielectric value and surface potential in the PEDOT:PSS side. By combining s-SNOM and scanning Kelvin probe microscopy, a special region in PEDOT:PSS is observed with a sharp surface potential drop and low dielectric value. The results suggest the existence of space charge regions both in N–Si and PEDOT:PSS at the interface. These findings contribute the understanding of the physical properties of the silicon heterojunction and promise potential routes to enhance device efficiency.
关键词： poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate)/n-type silicon interface,scanning Kelvin probe microscopy,carrier redistribution,infrared scattering-type scanning near-field optical microscope
更新于2025-09-11 14:15:04
-
Inverse photonic design of functional elements that focus Bloch surface waves
摘要： Bloch surface waves (BSWs) are sustained at the interface of a suitably designed one-dimensional (1D) dielectric photonic crystal and an ambient material. The elements that control the propagation of BSWs are defined by a spatially structured device layer on top of the 1D photonic crystal that locally changes the effective index of the BSW. An example of such an element is a focusing device that squeezes an incident BSW into a tiny space. However, the ability to focus BSWs is limited since the index contrast achievable with the device layer is usually only on the order of Δn≈0.1 for practical reasons. Conventional elements, e.g., discs or triangles, which rely on a photonic nanojet to focus BSWs, operate insufficiently at such a low index contrast. To solve this problem, we utilize an inverse photonic design strategy to attain functional elements that focus BSWs efficiently into spatial domains slightly smaller than half the wavelength. Selected examples of such functional elements are fabricated. Their ability to focus BSWs is experimentally verified by measuring the field distributions with a scanning near-field optical microscope. Our focusing elements are promising ingredients for a future generation of integrated photonic devices that rely on BSWs, e.g., to carry information, or lab-on-chip devices for specific sensing applications.
关键词： focusing elements,scanning near-field optical microscope,integrated photonic devices,Bloch surface waves,photonic design
更新于2025-09-04 15:30:14