Optical tweezing beam control using liquid crystal adaptive optical elements

Liquid crystal (LC) adaptive optical elements are described, which provide an alternative to existing micropositioning technologies in optical tweezing. A full description of this work is given in [1]. An adaptive LC prism supplies tip/tilt to the phase profile of the trapping beam, giving rise to an available steering radius within the x-y plane of 10 μm. Additionally, a modally addressed adaptive LC lens provides defocus, offering a z-focal range for the trapping site of 100 μm. The result is full three-dimensional positional control of trapped particle(s) using a simple and wholly electronic control system. Compared to competing technologies, these devices provide a lower degree of controllability, but have the advantage of simplicity, cost and light efficiency. Furthermore, due to their birefringence, LC elements offer the opportunity of the creation of dual optical traps with controllable depth and separation.

TRANSIENT SCANNING ELECTRON BEAM ANNEALING METHODS USED TO STUDY DIFFUSION AND DEFECTS IN IMPLANTED SILICON.

Rapid thermal annealing of arsenic and boron difluoride implants, such as those used for source/drain regions in CMOS, has been carried out using a scanning electron beam annealer, as part of a study of transient diffusion effects. Three types of e-beam anneal have been performed, with peak temperatures in the range 900 -1200 degree C; the normal isothermal e-beam anneals, together with sub-second fast anneals and 'dual-pulse' anneals, in which the sample undergoes an isothermal pre-anneal followed by rapid heating to the required anneal temperature is less than 0. 5s. The diffusion occuring during these anneal cycles has been modelled using SPS-1D, an implant and diffusion modelling program developed by one of the authors. This has been modified to incorporate simulated temperature vs. time cycles for the anneals. Results are presented applying the usual equilibrium clustering model, a transient point-defect enhancement to the diffusivity proposed recently by Fair and a new dynamic clustering model for arsenic. Good agreement with SIMS measurements is obtained using the dynamic clustering model, without recourse to a transient defect model.

Mn implanted GaAs by low energy ion beam deposition

High dose Mn was implanted into semi-insulating GaAs substrate to fabricate embedded ferromagnetic Mn-Ga binary particles by mass-analyzed dual ion beam deposit system at room temperature. The properties of as-implanted and annealed samples were measured with X-ray diffraction, high-resolution X-ray diffraction to characterize the structural changes. New phase formed after high temperature annealing. Sample surface image was observed with atomic force microscopy. All the samples showed ferromagnetic behaviour at room temperature. There were some differences between the hysteresis loops of as-implanted and annealed samples as well as the cluster size of the latter was much larger than that of the former through the surface morphology. (C) 2004 Elsevier B.V. All rights reserved.

(Ga, Gd, As) film growth on GaAs substrate by low-energy ion-beam deposit

(Ga, Gd, As) film was fabricated by the mass-analyzed dual ion-beam epitaxy system with the energy of 1000 eV at room temperature. There was no new peak found except GaAs substrate peaks (0 0 2) and (0 0 4) by X-ray diffraction. Rocking curves were measured for symmetric (0 0 4) reflections to further yield the lattice mismatch information by employing double-crystal X-ray diffraction. The element distributions vary so much due to the ion dose difference from AES depth profiles. The sample surface morphology indicates oxidizing layer roughness is also relative to the Gd ion dose, which leads to islandlike feature appearing on the high-dose sample. One sample shows ferromagnetic behavior at room temperature. (C) 2003 Elsevier B.V. All rights reserved.

1.55-mu m ridge DFB laser integrated with a buried-ridge-stripe dual-core spot-size converter by quantum-well intermixing

A ridge distributed feedback laser monolithically integrated with a buried-ridge-stripe spot-size converter operating at 1.55 mu m was successfully fabricated by means of low-energy ion implantation quantum-well intermixing and dual-core technologies. The passive waveguide was optically combined with a laterally exponentially tapered active core to control the mode size. The devices emit in a single transverse and single longitudinal mode with a sidemode suppression ratio of 38.0 dB. The threshold current was 25 mA. The beam divergence angles in the horizontal and vertical directions were as small as 8.0 degrees x 12.6 degrees, respectively, resulting in 3.0-dB coupling loss with a cleaved single-mode optical fiber.

Laser diode monolithically integrated with an electroabsorption modulator and dual-waveguide spot-size converter

A 1.60-mu m laser diode and electroabsorption modulator monolithically integrated with a dual-waveguide spot-size converter output for low-loss coupling to cleaved single-mode optical fiber is demonstrated. The devices emit in a single transverse and quasi-single longitudinal mode with a side mode suppression ratio of 25.6 dB. These devices exhibit a 3-dB modulation bandwidth of 16.0 GHz, and modulator extinction ratios of 16.2 dB dc. The beam divergence angle is about 7.3x10.6 deg, resulting in 3.0-dB coupling loss with cleaved single-mode optical fiber. (c) 2005 Society of Photo-optical Instrumentation Engineers.

Monolithically integrated semiconductor optical amplifier and electroabsorption modulator with dual-waveguide spot-size converter input and output

We have demonstrated an electroabsorption modulator and semiconductor optical amplifier monolithically integrated with novel dual-waveguide spot-size converters (SSC) at the input and output ports for low-loss coupling to a planar light-guide circuit silica waveguide or cleaved single-mode optical fibre. The device was fabricated by means of selective-area MOVPE growth, quantum well intermixing and asymmetric twin waveguide technologies with only a three-step low-pressure MOVPE growth. For the device structure, in the SOA/EAM section, a double ridge structure was employed to reduce the EAM capacitances and enable high bit-rate operation. In the SSC sections, buried ridge structure (BRS) was incorporated. Such a combination of ridge, ATG and BRS structure is reported for the first time in which it can take advantage of easy processing of the ridge structure and the excellent mode characteristic of BRS. At the wavelength range of 1550-1600 nm, lossless operation with extinction ratios of 25 dB dc and more than 10 GHz 3 dB bandwidth is successfully achieved, The beam divergence angles of the input and output ports of the device are as small as 8.0 degrees x 12.6 degrees, resulting in 3.0 dB coupling loss with a cleaved single-mode optical fibre.

Monolithically integrated laser diode and electroabsorption modulator with dual-waveguide spot-size converter input and output

We have demonstrated a 1.60 mu m ridge-structure laser diode and electroabsorption modulator monolithically integrated with buried-ridge-structure dual-waveguide spot-size converters at the input and output ports for low-loss coupling to a cleaved single-mode optical fibre by means of selective area growth and asymmetric twin waveguide technologies. The devices emit in single transverse and quasi-single longitudinal modes with a side mode suppression ratio of 25.6 dB. These devices exhibit 3 dB modulation bandwidth of 15.0 GHz and modulator extinction ratios of 14.0 dB dc. The output beam divergence angles of the spot-size converter in the horizontal and vertical directions are as small as 7.3 degrees x 10.6 degrees, respectively, resulting in 3.0 dB coupling loss with a cleaved single-mode optical fibre.

Lossless electroabsorption modulator monolithically rntegrated with a semiconductor optical amplifier and dual-wavegulde spot-size converters

Semiconductor optical amplifier and electroabsorption modulator monolithically integrated with dual-waveguide spot-size converters at the input and output ports is demonstrated by means of selective area growth, quantum-well intermixing, and asymmetric twin waveguide technologies. At the wavelength range of 1550 similar to 1600 nm, lossless operation with extinction ratios of 25-dB dc and 11.8-dB radio frequency and more than 10-GHz 3-dB modulation bandwidth is successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3 degrees x 10.6 degrees, respectively, resulting in 3.0-dB coupling loss with cleaved single-mode optical fiber.

Laser diode integrated with a dual-waveguide spot-size converter by low-energy ion implantation quantum well intermixing

A ridge laser diode monolithically integrated with a buried-ridge-structure dual-waveguide spot-size converter operating at 1.58 mu m is successfully fabricated by means of low-energy ion implantation quantum well intermixing and asymmetric twin waveguide technology. The passive waveguide is optically combined with a laterally tapered active core to control the mode size. The devices emit in a single transverse and quasi single longitudinal mode with a side mode suppression ratio of 40.0dB although no grating is fabricated in the LD region. The threshold current is 50 mA. The beam divergence angles in the horizontal and vertical directions are as small as 7.3 degrees x 18.0 degrees, respectively, resulting in 3.0dB coupling loss With a cleaved single-mode optical fibre.

Electroabsorption-Modulated DFB laser Integrated.With dual-core spot-size converters

A 1.55-mu m single shallow ridge electroabsorptionmodulated distributed feedback laser that is monolithically integrated with a buried-ridge-stripe dual-core spot-size converter (SSC) at the input and output ports was fabricated by combining selective area growth, quantum-well intermixing, and dual-core integration techniques simultaneously. These devices exhibit a threshold current of 34 mA, a side mode suppression ratio of 38.0 dB, a 3-dB modulation bandwidth of 11.0 GHz, and a modulator extinction ratio of 25.0 dB dc. The output beam divergence angles of the SSC in the horizontal and vertical directions are as small as 7.3 degrees x 18 degrees, respectively, resulting in 3.2-dB coupling loss with a cleaved single-mode optical fiber.

1.55-mu m Ridge DFB laser and electroabsorption modulator integrated with buried-ridge-stripe dual-waveguide spot-size converter output

A 1.55-mu m ridge distributed feedback laser and electroabsorption modulator monolithically integrated with a buried-ridge-stripe dual-waveguide spot-size converter (SSC) at the output port for low-loss coupling to a cleaved single-mode optical fiber was fabricated by means of selective area growth, quantum-well intermixing, and dual-core technologies. These devices exhibit threshold current of 28 mA, 3-dB modulation bandwidth of 12.0 GHz, modulator extinction ratios of 25.0-dB dc. The output beam divergence angles of the SSC in the horizontal and vertical directions are as small as 8.0 degrees x 12.6 degrees, respectively, resulting in 3.2-dB coupling loss with a cleaved single-mode optical fiber.

Influence of dual incorporation of In and N on the luminescence of GaInNAs/GaAs single quantum wells

The optical properties of above- and below-band-edge transitions have been investigated by incorporating In atoms into GaNAs/GaAs single quantum wells. The experimental results show that with increasing In concentration the interband luminescence is improved and the luminescence intensity below the band edge in GaInNAs/GaAs decreases significantly. An interpretation is given that N atoms are preferable to form a covalent bond with In than with Ga atoms in a GaInNAs alloy, due to the compensation of the atomic-size difference between In and N atoms on the GaAs substrate. The photoreflectance spectra of the GaInNAs/GaAs single quantum well support the assignment of an intrinsic mechanism to the high-energy luminescence peak. (C) 2000 American Institute of Physics. [S0003- 6951(00)01752-6].

A study of the interface of CeO2/Si heterostructure grown by ion beam deposition

Epitaxial cerium dioxide films on single-crystal silicon substrates (CeO2/Si) have been grown by a dual mass-analyzed low-energy ion beam deposition (IBD) system. By double-crystal X-ray diffraction (XRD), Full Width at Half Maximum (FWHM) are 23' and 33' in the rocking curves for (222) and (111) faces of the CeO2 film, respectively, and the lattice-mismatch Delta a/a with the substrate is about - 0.123%. The results show that the CeO2/Si grown by IBD is of high crystalline quality. In this work, the CeO2/Si heterostructure were investigated by X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) measurements. Especially, XPS and AES depth profiling was used to analyze the compositions and structures in the interface regions of the as-grown and post-annealed CeO2/Si. It was found that there was no silicon oxide in the interface region of the as-grown sample but silicon oxide in the post-annealed sample. The reason for obtaining such high quality heterostructure mainly depends on the absence of silicon oxide in the surface at the beginning of the deposition. (C) 1998 Elsevier Science Ltd. All rights reserved.

Electroabsorption-modulated DFB laser integrated with dual-waveguide spot-size converter - art. no. 60200N

A 1.55-mu m ridge DFB laser and electroabsorption modulator monolithically integrated with a buried-ridge-stripe dual-waveguide spot-size converter at the output port for low-loss coupling to a cleaved single-mode optical fiber was fabricated by means of selective area growth, quantum well intermixing and dual-core technologies. These devices exhibit threshold current of 28 mA, side mode suppression ratio of 38.0 dB, 3-dB modulation bandwidth of 12.0 GHz, modulator extinction ratios of 25.0 dB dc. The output beam divergence angles of the spot-size converter in the horizontal and vertical directions are as small as 8.0 degrees x 12.6 degrees, respectively, resulting in 3.2 dB coupling loss with a cleaved single-mode optical fiber.