A novel butt-joint scheme for the preparation of electro-absorptive lasers

A 1.55 mu m InGaAsP/InGaAsP multiple-quantum-well electro-absorption modulator (EAM) monolithically integrated with a distributed feedback laser (DFB) diode has been realized based on a novel butt-joint scheme by ultra-low metal-organic vapour phase epitaxy for the first time. The threshold current of 25 mA and an extinction ratio of more than 30 dB are obtained by using the novel structure. The beam divergence angles at the horizontal and vertical directions are as small as 19.3 degrees x 13 degrees, respectively, without a spot-size converter by undercutting the InGaAsP active region. The capacitance of the ridge waveguide device with a deep mesa buried by polyimide was reduced down to 0.30 pF.

Rearrangeable nonblocking SOI waveguide thermooptic 4x4 switch matrix with low insertion loss and fast response

A rearrangeable nonblocking 4 x 4 thermooptic silicon-on-insulator waveguide switch matrix at 1.55-mu m integrated spot size converters is designed and fabricated for the first time. The insertion losses and polarization-dependent losses of the four channels are less than 10 and 0.8 dB, respectively. The extinction ratios are larger than 20 dB. The response times are 4.6 mu s for rising edge and 1.9 mu s for failing edge.

A silicon-on-insulator-based thermo-optic waveguide switch with low insertion loss and fast response

A silicon-on-insulator-based thermo-optic waveguide switch integrated with spot size converters is designed and fabricated by inductively coupled plasma reactive ion etching. The device shows good characteristics, including low, insertion loss of 8 +/- 1 dB for wavelength 1530-1580 nm and fast response times of 4.6 As for rising edge and 1.9 mu s for failing edge. The extinction ratios of the two channels are 19.1 and 18 dB, respectively.

Plasmonic very-small-aperture lasers

The fabrication of plasmonic very-small-aperture lasers is demonstrated in this letter. It is an integration of the surface plasmon structures and very-small-aperture lasers (VSAL). The experimental and numerical results demonstrate that the transmission field can be confined to a spot with subwavelength width in the far field, and the power output can be enhanced 140% of the normal VSAL. Such a device can be useful in the application of a high resolution far-field scanning optical microscope. (C) 2007 American Institute of Physics.

Improving the optical profile of electroabsorption modulator using single-sided large optical cavity structure

An electroabsorption modulator with large optical cavity was designed and fabricated successfully. Both the simulated and experimental results show that, the larger optical cavity structure introduced could obviously improve the optical profile of EA modulator, the traditional elliptical near-field spot becomes more rounded, so it will match better with the optical fiber and is beneficial for raising the coupling efficiency.

Numerical study of a high-resolution far-field scanning optical microscope via a surface plasmon-modulated light source

In this paper, we analyze light transmission through a single subwavelength slit surrounded by periodic grooves in layered films consisting of An and dielectric material. A subwavelength grating is scanned numerically by the finite difference time domain method in two dimensions. The results show that the transmission field can be confined to a spot with subwavelength width in the far field and can be useful in the application of a high-resolution far-field scanning optical microscope.

Submicrosecond rearrangeable nonblocking silicon-on-insulator thermo-optic 4 X 4 switch matrix

A rearrangeable nonblocking silicon-on-insulator-based thermo-optic 4 X 4 switch matrix is designed and fabricated. A spot-size converter is integrated to reduce the insertion loss, and a new driving circuit is designed to improve the response speed. The insertion loss is less than 10 dB, and the response time is 950 us. (c) 2007 Optical Society of America

SOI-based 16x16 thermo-optic waveguide switch matrix

A 16 x 16 thermo-optic wavelenght switch matrix has been designed and febricated on silicon-on-insulator wafer. For reducing device lenght, blocking switch matrix configuration is chosen. The building block of a matix is a 2 x 2 cell with Mach-Zehnder interferometer configuration, where a multi-mode interferometer serves as splitters/combiners. Spot size converters and isolating grooves are integrated on the same chip to reduce loss and power consumption. Average power consumption of the switch cell is 220 mW. The switching time of a switch cell is less than 3 mu s.

End-pumped continuous-wave passively modelocked Nd : YVO4 laser with low pump power

A simple cw mode-locked solid-state laser, which is end-pumped by a low-power laser diode, was demonstrated by optimizing the laser-mode size inside the gain medium. The optimum ratio between mode and pump spot sizes inside the laser crystal was estimated for a cw mode-locked laser, taking into account the input pump power. Calculation and experiment have shown that the optimum ratio was about 3 when the pump power is 2 W, which is different from the value regularly used in passively mode-locked solid-state lasers. This conclusion is also helpful in increasing the efficiency of high-power ultrashort lasers. (C) 2006 Society of Photo-Optical Instrumentation Engineers.

Detect the sub-wavelength data by applying a very-small-aperture laser

We present a theoretical and experimental research about applying a very-small-aperture laser (VSAL) to detect sub-wavelength data. Near-field distribution of a VSAL, which is essential for the application of such near-field devices, will be affected by the sample or fiber posited in the near-field region of the aperture. When the device is applied to detect the sub-wavelength data, the real resolution depends on the near-field spot size, the divergent angle of the beam and the distance from the aperture to the sample. Experimental results, including the near-field detection of the spot and detection of the sub-wavelength data by using the VSAL, are presented in this paper. We realize the two dimensional scanning about the sub-wavelength data (with the width 600 nm) by employing a VSAL with a 300 nm x 300 nm aperture.

Near-field scanning optical microscopy with an active probe

A near-field scanning optical microscopy (NSOM) system employing a very-small-aperture laser (VSAL) as an active probe is reported in this Letter. The VSAL in our experiment has an aperture size of 300 nmx300 nm and a near-field spot size of about 600 nm. The resolution of the NSOM system with the VSAL can reach about 600 nm, and even 400 nm. Considering the high output power of the VSAL, such a NSOM system is a potentially useful tool for nanodetection, data storage, nanolithography, and nanobiology.

Semiconductor optical amplifier optical gate with graded strained bulk-like active structure

A novel semiconductor optical amplifier (SOA) optical gate with a graded strained bulk-like active structure is proposed. A fiber-to-fiber gain of 10 dB when the coupling loss reaches 7 dB/factet and a polarization insensitivity of less than 0.9 dB for multiwavelength and different power input signals over the whole operation current are obtained. Moreover, for our SOA optical gate, a no-loss current of 50 to 70 mA and an extinction ratio of more than 50 dB are realized when the injection current is more than no-loss current, and the maximum extinction ratio reaches 71 dB, which is critical for crosstalk suppression. (C) 2003 society of Photo-Optical Instrumentation Engineers.

First charge collection and position-precision data on the medium-resistivity silicon strip detectors before and after neutron irradiation up to 2x10(14) n/cm(2)

Test strip detectors of 125 mu m, 500 mu m, and 1 mm pitches with about 1 cm(2) areas have been made on medium-resistivity silicon wafers (1.3 and 2.7 k Ohm cm). Detectors of 500 mu m pitch have been tested for charge collection and position precision before and after neutron irradiation (up to 2 x 10(14) n/cm(2)) using 820 and 1030 nm laser lights with different beam-spot sizes. It has been found that for a bias of 250 V a strip detector made of 1.3 k Ohm cm (300 mu m thick) can be fully depleted before and after an irradiation of 2 x 10(14) n/cm(2). For a 500 mu m pitch strip detector made of 2.7 k Ohm cm tested with an 1030 nm laser light with 200 mu m spot size, the position reconstruction error is about 14 mu m before irradiation, and 17 mu m after about 1.7 x 10(13) n/cm(2) irradiation. We demonstrated in this work that medium resistivity silicon strip detectors can work just as well as the traditional high-resistivity ones, but with higher radiation tolerance. We also tested charge sharing and position reconstruction using a 1030 nm wavelength (300 mu m absorption length in Si at RT) laser, which provides a simulation of MIP particles in high-physics experiments in terms of charge collection and position reconstruction, (C) 1999 Elsevier Science B.V. All rights reserved.