Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Focusing of Light in the Eye

Focusing of Light in the Eye

Light rays enter the eye through the cornea, a transparent dome-shaped tissue that is the eye's outermost layer. The cornea bends or refracts, light rays traveling to the pupil. The shape of the cornea determines how much of the light is bent and whether the image will be focused correctly on the retina at the back of the eye. Once the light has passed through both refraction layers, it converges into a single focal point onto a small area. This is where photoreceptors start transforming...

Angular Momentum

Angular Momentum

Angular momentum characterizes an object's rotational motion and is defined as the moment of its linear momentum about a specified point O. When a particle moves along a curved path in the x-y plane, the scalar formulation calculates the magnitude of its angular momentum, utilizing the moment arm (d), representing the perpendicular distance from point O to the line of action of the linear momentum. Despite being scalar in formulation, angular momentum is inherently a vector quantity. Its...

Conservation of Angular Momentum: Application

Conservation of Angular Momentum: Application

A system's total angular momentum remains constant if the net external torque acting on the system is zero. Examples of such systems include a freely spinning bicycle tire that slows over time due to torque arising from friction, or the slowing of Earth's rotation over millions of years due to frictional forces exerted on tidal deformations. However in the absence of a net external torque, the angular momentum remains conserved. The conservation of angular momentum principle requires a...

Circular Orbits and Critical Velocity for Satellites

Circular Orbits and Critical Velocity for Satellites

The Moon orbits around the Earth. In turn, the Earth (and other planets) orbit the Sun. The space directly above our atmosphere is filled with artificial satellites in orbit. One can examine the circular orbit, the simplest kind of orbit, to understand the relationship between the speed and the period of planets and satellites with respect to their positions and the bodies that they orbit.
Nicolaus Copernicus (1473-1543) first suggested that the Earth and all other planets orbit the Sun in...

Angular Momentum about an Arbitrary Axis

Angular Momentum about an Arbitrary Axis

Imagine a rigid body with a mass denoted as 'm', which has its center of mass at point G and is rotating around an inertial reference frame. The angular momentum at an arbitrary point P can be calculated by taking the cross product of the position vector and linear momentum vector for each individual mass element.
The velocity of a mass element comprises its translational velocity and the relative velocity instigated by the body's rotation. Substituting the velocity equation into...

Conservation of Angular Momentum

Conservation of Angular Momentum

A system's total angular momentum remains constant if the net external torque acting on the system is zero. Considering a system that consists of n tiny particles, the angular momentum of any tiny particle may change, but the system's total angular momentum would remain constant. The principle of conservation of angular momentum only considers the net external torque acting on the system. While there are internal forces exerted by different particles within the system that also produce...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Real-time visualization of transient terahertz waveforms emitted from a resonant tunneling diode.

Optics express·2025

Same author

Lamb-dip spectroscopy of rotational levels with photomixing terahertz emitter.

Optics express·2025

Same author

Early-Phase Intervention With Traditional Japanese Acupuncture and Moxibustion for Fibromyalgia: A Case Report.

Cureus·2024

Same author

Parkinson's Disease Bradykinesia, Forward Posture, and Drug-Induced Pisa Syndrome Alleviated With Traditional Japanese Acupuncture: A Case Report.

Cureus·2024

Same author

Achieved Weight Gain and Return to Work After Intervention With Traditional Japanese Acupuncture for Avoidant Restrictive Food Intake Disorder: A Case Report.

Cureus·2024

Same author

Phase-resolved measurement and control of ultrafast dynamics in terahertz electronic oscillators.

Nature communications·2024

Search research articles

Related Experiment Video

Updated: Feb 25, 2026

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station

Published on: April 1, 2020

Focusing light with orbital angular momentum by circular array antenna.

Takashi Arikawa, Shohei Morimoto, Koichiro Tanaka

|August 10, 2017

Summary

This summary is machine-generated.

Researchers focused light carrying orbital angular momentum (OAM) using a circular antenna array in the terahertz region. This technique achieves deep subwavelength focusing, enabling new observations in physics.

More Related Videos

Construction and Operation of a Light-driven Gold Nanorod Rotary Motor System

Construction and Operation of a Light-driven Gold Nanorod Rotary Motor System

Published on: June 30, 2018

3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles

3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles

Published on: October 1, 2014

Related Experiment Videos

Last Updated: Feb 25, 2026

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station

Published on: April 1, 2020

Construction and Operation of a Light-driven Gold Nanorod Rotary Motor System

Construction and Operation of a Light-driven Gold Nanorod Rotary Motor System

Published on: June 30, 2018

3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles

3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles

Published on: October 1, 2014

Area of Science:

Optics and Photonics
Antenna Engineering
Terahertz Science

Background:

Orbital angular momentum (OAM) enables unique light properties.
Focusing light with OAM is crucial for advanced applications.
Terahertz (THz) frequency region offers unique research opportunities.

Purpose of the Study:

To demonstrate deep subwavelength focusing of light with OAM.
To investigate the use of antenna arrays for OAM beam manipulation.
To enable observation of dipole-forbidden transitions using OAM vortex beams.

Main Methods:

Experimental generation of a vortex beam with OAM (ħ) using a spiral phase plate in the THz region.
Utilizing an 8-element circular array of linear antennas for focusing.
Direct measurement of the phase vortex using THz near-field microscopy.

Main Results:

Achieved focusing of THz vortex beams with OAM.
Observed a beam profile with a central dark spot and 2π phase rotation.
Reduced beam size by a factor of 3.4 ± 0.2.
Identified half-wave resonance of antenna elements as the focusing mechanism.

Conclusions:

Demonstrated a novel method for deep subwavelength focusing of OAM light.
The antenna-based focusing method is scalable to other frequency regions.
This technique overcomes limitations in observing dipole-forbidden transitions with OAM vortex beams.