Takaaki Mukai

Chapter 3 Optical Amplification by Semiconductor Lasers

Publisher Summary This chapter discusses the design and operating characteristics of optical amplifiers that have structures similar to semiconductor lasers. Because the semiconductor lasers inherently contain light amplification processes by stimulated emission, they can be utilized as optical amplifiers besides oscillators. The chapter concentrates on the device characteristics of a linear amplifier. It describes characteristics for injection-locked laser amplifiers. Optical frequency-modulated (FM) signal amplification and FM noise reduction are also discussed in the chapter. The chapter provides a look at system applications for these amplifiers. The linear amplifier is evaluated as a preamplifier and as a linear repeater in terms of the signal-to-noise ratio. System performance features confirmed in experiments are discussed and applications of injection-locked amplifiers to intensity-modulated (IM) and FM signals are reviewed in the chapter.

Volumetric Display System Using a Digital Micromirror Device Based on Inclined-Plane Scanning

Experimental results of a volumetric display system based on three-dimensional (3D) scanning using an inclined image are reported. An optical real image of an inclined two-dimensional (2D) display device is moved laterally by an optical mirror scanner. Inclined cross-sectional images of a 3D object are projected in accordance with the position of the image plane. A 3D real image is formed as a stack of 2D cross-sectional images as a result of high-speed scanning. This 3D image can satisfy all the criteria for stereoscopic vision. An experimental system using a galvanometer mirror and a digital micromirror device was constructed, and generated three-dimensional images consisting of 1024×768×200 voxels. A multilevel image can be formed by a spatial dithering technique, even though the binary display device was used.

Volumetric display using rotating prism sheets arranged in a symmetrical configuration

A volumetric display that creates a distortion-free three-dimensional (3D) image in midair is described. The proposed system consists of rotating prism sheets used as an optical scanner and a dihedral corner reflector array (DCRA), which is a distortion-free imaging element. Two prism sheets are arranged in a symmetrical configuration to reduce an unnatural motion parallax caused by optical aberrations. A cross-section of the 3D image is formed by the DCRA in midair and moved by the rotating prism sheets to create a 3D displayable space. A 3D volume image was displayed without image distortion or unnatural motion parallax.

Floating volumetric image formation using a dihedral corner reflector array device

A volumetric display system using an optical imaging device consisting of numerous dihedral corner reflectors placed perpendicular to the surface of a metal plate is proposed. Image formation by the dihedral corner reflector array (DCRA) is free from distortion and focal length. In the proposed volumetric display system, a two-dimensional real image is moved by a mirror scanner to scan a three-dimensional (3D) space. Cross-sectional images of a 3D object are displayed in accordance with the position of the image plane. A volumetric image is observed as a stack of the cross-sectional images. The use of the DCRA brings compact system configuration and volumetric real image generation with very low distortion. An experimental volumetric display system including a DCRA, a galvanometer mirror, and a digital micro-mirror device was constructed to verify the proposed method. A volumetric image consisting of 1024×768×400 voxels was formed by the experimental system.

Volumetric display using a rotating prism sheet as an optical image scanner

We developed a volumetric display that uses a rotating prism sheet as an optical scanner. A cross-sectional image of a three-dimensional (3D) object was moved laterally by the rotating prism sheet. A stack of the cross-sectional images constructed a 3D volume image that satisfies all requirements of stereoscopic vision. Since the mechanical load of the proposed scanning method was small, it is easy to enlarge the effective area of the scanner and its scanning area. We used a concave mirror to collimate rays emitted from each point to reduce the aberration caused at the prism sheet. A displayed 3D image had a size of 7 cm × 5 cm × 7 cm and a resolution of 1024 × 768 × 200 voxels.

Floating three-dimensional display viewable from 360 degrees

The aim of this research is to develop a full-parallax auto-stereoscopic display system, which can generate a floating three-dimensional (3-D) image viewable from a surrounding area. A 3-D display method based on the combination of integral imaging, 360-degree scanning with a rotating mirror, and imaging in the air with a concave mirror is proposed. A scanning system is composed of a hemisphere concave mirror and a mirror scanner, which is located around the center of the concave mirror. By putting an image generated by an integral imaging system into the scanning system, a floating stereoscopic image can be formed around the center of the concave mirror. When the mirror scanner rotates and the image on the integral imaging system is switched in accordance with mirror angle, each directional image can be observed from each viewing angle. The feasibility of the proposed method was examined by preliminary experiments. The abilities of generation of a floating full-parallax image and a floating auto-stereoscopic image with 360-degree viewing angle are demonstrated.

Floated integral imaging display viewable from surrounding area

A full-parallax auto-stereoscopic display method that enables formation of a floating three-dimensional image viewable from a surrounding area is proposed. This method utilizes integral imaging, a rotating mirror scanner, and a hemisphere concave mirror.

Volumetric display based on optical scanning of an inclined image plane by an image rotator and imaging by a dihedral corner reflector array

We propose to use a rotational optical scanning method for a volumetric three-dimensional (3D) display based on optical scanning of an inclined image plane. The image plane was moved by an image rotator and formed by a dihedral corner reflector array, which is a distortion free imaging element forming a real image at a plane-symmetrical position. A stack of the moved and formed image planes of a two-dimensional (2D) display created displayable space of a 3D image, which satisfies all the criteria of stereoscopic vision and can be seen by the naked eyes. The image rotator used in this study was constructed of prism sheets and planar mirrors. The image plane was moved rotationally by rotating the proposed image rotator on an axis parallel to the mirror plane. Enlargement of the displayable space is achieved by just extending the distance between the 2D display and the mirror, so that the proposed scanning method is effective to display a large 3D image for our volumetric display system. We made a prototype display and observed a moved image plane to measure the displayable space of the 3D image. The size of the displayable space was 1200 [cm3] that is approximately six times as large as our previous display using a translational optical scanning method.

Self-pumped phase conjugate mirror using a broad-area laser diode

Self-pumped phase conjugate mirror is successfully constructed using a broad-area laser diode with angled feedback configuration. We demonstrate the light output decrease and the half-axial mode specific to the phase conjugate resonator.

Real-Time Updatable Volumetric Display System Based on Inclined-Image Scanning

A new experimental volumetric display system based on inclined-image scanning is reported. A volumetric image is formed as a stack of about one hundred cross-sectional images. A high-speed video interface apparatus for controlling a digital micromirror device, which displays the cross-sectional images, is introduced to achieve real-time updating of volumetric images. The cross-sectional images of a three-dimensional (3D) object are generated from a depth map of the 3D polygon surface model within a video frame rate. In addition, to increase the viewing angle, the numerical aperture of an optical system is in-creased by use of a larger scanner mirror.