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Results for “transmittance”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Dual-polarization O-band silicon photonics transmitter with an integrated tunable laser, Mach-Zehnder modulators, and SOAs

Presented is an O-band silicon photonics dual-polarization coherent/IMDD modulator integrated with semiconductor optical amplifiers and tunable laser to enhance the short-reach link budget. The laser demonstrated output power >6 dBm and a <250 kHz linewidth over a 14 nm tuning range. Modulators paired with custom 64 Gbaud QPSK drivers exhibited improved analog link sensitivity compared to similar devices without integrated gain sections. They also demonstrated 53 Gbaud dual-polarization PAM4 operation when characterized with a linear driver and MaxLinear 100G/lane DSP board. Both optical links achieved BERs at the KP4-FEC threshold and overall transmitter assembly energy consumption <6.9 pJ/bit without any thermal control when at steady room temperatures.

Liu, Junqian (ORCID:0000000167337650)↗
DOE OSTI2021

Leaf spectral reflectance and transmittance, San Lorenzo, Panama, 2020

This data package contains full-range (350 – 2500 nm) leaf reflectance and transmittance spectra of leaves collected at the San Lorenzo forest canopy crane site in Panama (PA-SLZ) from January to March 2020. Around 1000 leaves were measured from 50 species and various leaf phenological stages. Leaves were sampled from both the top of the canopy and multiple heights within the canopy from 10 vertical profiles and for six core species, from the top of the canopy. This data package includes processed leaf spectra (*.csv), and raw data from the spectroradiometer (compressed as .zip). Metadata files include data descriptions (_dd.csv) for tabular data and sample information and a description of the field campaign protocol (PA-SLZ_2020_Protocol.pdf). In addition to the leaf spectral measurements included here, these samples were also used for measurement of leaf gas exchange, carbon and nitrogen content and leaf mass per unit leaf area (LMA) contained in related data packages.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Leaf reflectance, leaf transmittance and sky irradiance, at four sites in Panama, 2022

Paired leaf reflectance and transmittance data measured in Panama, at the Parque Natural Metropolitano (PNM), on Barro Colorado Island (BCI), at the San Lorenzo canopy crane site (SLZ), and in Gamboa, Panama from January to April 2022. Measurements were made on leaves from 57 different tree, shrub and liana species, from sunlit canopy and understory locations. Bark reflectance was also measured on the trunks of common tree species at the PNM and SLZ sites. Also included are irradiance measurements and leaf area index (LAI) from eight vertical profiles at PNM. The aim of these data was to refine our understanding of vertical trait and environmental variation in tropical forests, and to improve models which can predict leaf traits from leaf contact spectral measurements. All spectral data and metadata are presented in .csv files and complete instrument output are included in .zip folders. Protocol details are provided as pdf documents. In addition to spectral data described here, some of these samples were also used for measurement of leaf gas exchange, carbon and nitrogen content, and leaf mass per unit leaf area (LMA) these data can be cross linked using the unique sample ID and are provided in separate related data packages.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

A Miniaturized Long-Life, Low-Frequency Acoustic Transmitter for Fish Tracking in Marine Environment - CRADA 447

Advance state-of-art technologies for tracking marine mammals, fish, sea turtles, and other protected species, based on acoustic telemetry. Objectives include: (1) develop a new acoustic transmitter that has a greatly improved detection range and service life while being significantly smaller and lighter than the existing commercial counterparts; and (2) reach a TRL of 5 so the technology is ready for organizations interested in small- or medium-scale field trials.

42 ENGINEERING↗
DOE OSTI2023

Wireless System Development for GaN-Based Transmitters for Advanced Nuclear Reactor Environments

The market for consumer electronics is dominated by Si-based electronics. Many Si-based complementary metal–oxide–semiconductor (CMOS) devices are reaching their limitations in terms of switching frequencies, voltages, currents, and temperatures. Furthermore, these devices are widely known to be susceptible to ionizing radiation and neutrons. Advanced nuclear reactors, especially microreactors and small modular reactors, require wireless electronics that can survive larger neutron and gamma doses than Si CMOS. Because of their size, electronics will need to be placed closer to the reactor cores, and cabling capabilities may be limited. However, GaN high-electron-mobility transistors (HEMTs) have been shown to switch faster with higher gains, and they can achieve current and voltage limits beyond traditional Si CMOS. However, they have less market maturity and have undergone less testing. These GaN HEMTs have been shown to survive ionizing radiation with little effects, but the effects of neutron radiation remain widely unknown. In this report, a wireless electronic system capable of supporting multiple radiation-hardened (rad-hard) sensors is presented. The proposed transmission scheme was designed to be simple to increase the likelihood of success in the immature GaN HEMT process and in high-radiation environments. The transmission system was tested using software-defined radios to emulate the transmission scheme before the transmitter circuitry in the GaN process was developed.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1965

Solid-state laser transmitter is amplitude modulated

Amplitude modulated laser transmitter affords radio frequencies unlimited bandwidth. The system, which is solid state and compact, uses a gallium arsenide diode that emits in the near infrared.

Bilderback, R.↗
NASA NTRS1966

High-power transmitter development

Klystron filament current and voltage remote- metering circuits for high power transmitter of deep space instrumentation facility

REMOTE CONTROL↗