Neareld optical microscopy and spectroscopy is emerging as a powerful tool for the investigation of semiconductor structures. Tunable excitation combined with subwavelength resolution is providing an unprecedented level of detail on the local optical properties of semiconductor structures. Recent neareld optical studies have addressed issues of laser diode mode pro ling, minority carrier transp...

An experiment on the phase stability of an injection-locked beam was done by using AlGaAs semiconductor lasers. The coherence of two beams from master and slave lasers was measured by interference between the beams in the Twymann-Green interferometer. The phase change of the output beam of the slave laser as a function of the driving current was measured in a Mach-Zehnder interferometer consist...

In this paper we modeled and analyzed the ridge type InGaAlAs/InP semiconductor laser with lateral current confinement structure, and optimized the design for the ridge wave guide with the current confinement. We proposed and fabricated the ridge type InGaAlAs/InP laser with a cost effective selective undercut etching method and demonstrated the improvement of the ridge laser performance. This ...

   Self-heating leads to a temperature rise of the laser diode and limits the output power and efficiency due to increased loss and decreased differential gain. To control device self-heating, it is required to design the laser structure with a low optical loss, while the heat flux must spread out of the device efficiently. In this study, a new asymmetric waveguide design is proposed and th...

We propose and experimentally demonstrate a triple-wavelength fiber ring laser using a semiconductor optical amplifier (SOA) in conjunction with an array waveguide grating (AWG). The experimental results show three lasing lines with an adjustable wavelength separation and a large optical signal-to-noise ratio under room temperature. The three channels operate at 1531.5 nm, 1532.3 nm and 1533.1 ...

A welding seam tracking visual sensor based on laser scanning is designed to solve the problems, such as indistinct image, difficulty in processing image etc., caused by serious arc light interference during welding. This visual sensor is mainly composed of a scanning motor, a linear-array CCD, a scanning rotating mirror and a semiconductor laser. Because the sensor measurement precision relies...

Laser speckle contrast imaging (LSCI) has emerged as a valuable tool for cerebral blood flow (CBF) imaging. We present a multi-exposure laser speckle imaging (MESI) method which uses a high-frame rate acquisition with a negligible inter-frame dead time to mimic multiple exposures in a single-shot acquisition series. Our approach takes advantage of the noise-free readout and high-sensitivity of ...

The transient photovoltaic (PV) characteristic of HgCdTe PV array is studied using an ultrafast laser. The photoresponse shows an apparent negative valley first, then it evolves into a positive peak. By employing a combined theoretical model of pn junction and Schottky potential, this photo-response polarity changing curves can be interpreted well. An obvious decreasing of ratio of negative val...

A field emitter array held at the threshold of emission by a dc gate potential from which current pulses are triggered by the application of a laser pulse on the backside of the semiconductor may produce electron bunches ~‘‘density modulation’’! at gigahertz frequencies. We develop an analytical model of such optically controlled emission from a silicon tip using a modified Wentzel– Kramers–Bri...