Design of a compact polarizing beam splitter based on a photonic crystal ring resonator with a triangular lattice

We propose and simulate a new kind of compact polarizing beam splitter (PBS) based on a photonic crystal ring resonator (PCRR) with complete photonic bandgaps. The two polarized states are separated far enough by resonant and nonresonant coupling between the waveguide modes and the microring modes. Some defect holes are utilized to control the beam propagation. The simulated results obtained by the finite-difference time-domain method show that high transmission (over 95%) is obtained and the polarization separation is realized with a length as short as 3.1 mu m. The design of the proposed PBS can be flexible, thanks to the advantages of PCRRs.

Realization of MMI power splitter by UV-light imprinting technique using hybrid sol-gel SiO2 materials

An efficient fabrication scheme of buried ridge waveguide devices is demonstrated by UV-light imprinting technique using organic-in organic hybrid sol-gel Zr-doped SiO2 materials. The refractive indices of a guiding layer and a cladding layer for the buried ridge waveguide structure are 1.537 and 1.492 measured at 1550 nm, respectively. The tested results show more circular mode profiles clue to existence of the cladding layer. A buried ridge single-mode waveguide operating at 1550 nm has a low propagation loss (0.088 dB/cm) and the 1 x 2 MMI power splitter exhibits uniform outputs, with a very low splitting loss of 0.029 dB at 1549 nm.

1.55 mu m Ge islands resonant-cavity-enhanced detector with high-reflectivity bottom mirror

A 1.55 mum Ge islands resonant-cavity-enhanced (RCE) detector with high-reflectivity bottom mirror was fabricated by a simple method. The bottom mirror was deposited in the hole formed by anisotropically etching in a basic solution from the back side of the sample with the buried SiO2 layer in silicon-on-insulator substrate as the etch-stop layer. Reflectivity spectrum indicates that the mirror deposited in the hole has a reflectivity as high as 99% in the range of 1.2-1.65 mum. The peak responsivity of the RCE detector at 1543.8 nm is 0.028 mA/W and a full width at half maximum of 5 nm is obtained. Compared with the conventional p-i-n photodetector, the responsivity of RCE detector has a nearly threefold enhancement. (C) 2004 American Institute of Physics.

High speed 2x2 optical switch in silicon-on-insulator based on plasma dispersion effect

Based on free carrier plasma dispersion effect, a 2 x 2 optical switch is fabricated in a silicon-on-insulator substrate by inductively coupled-plasma technology and ion implantation. The device has a Mach-Zehnder interferometer structure, in which two directional couplers serve as the power splitter and combiner. The switch presents an insertion loss of 3.04 dB and a response time of 496 ns.

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.

A 4x4 strictly nonblocking silicon-on-insulator thermo-optic switch matrix

A 4 x 4 strictly nonblocking thermo-optic switch matrix implemented with a 2 x 2 Mach-Zehnder switch unit was fabricated in silicon-on-insulator wafer. Insertion losses of the shortest and the longest path in the device are about 14.8 dB and 19.2 dB, respectively. The device presents a very low loss dependent on wavelength. For one switch unit, the power consumption needed for operation is measured to be 0.270 W-0.288 W and the switching time is about 13 +/- 1 mu s.

Design, fabrication, and characterization of an ultracompact low-loss photonic crystal corner mirror

An ultracompact, low-loss, and broad-band corner mirror, based on photonic crystals, is investigated in this paper. Based on the theoretical analysis of the loss mechanism, the boundary layers of the photonic crystal region are revised to improve the extra losses, and the transmission characteristics are evaluated by using the 3-D finite-difference time-domain method. The device with optimized structure was fabricated on silicon-on-insulator substrate by using electron-beam lithography and inductively coupled plasma etching. The measured extra losses are about 1.1 +/- 0.4 dB per corner mirror for transverse-electronic polarization for the scanning wavelength range of 1510-1630 nm. Dimensions of the achieved PC corner mirror are less than ;7 x 7 mu m(2), which are only about one tenth of conventional wave-guide corner mirrors.

Material growth and device fabrication of highly strained InGaAs/InGaAsP long wavelength distributed feedback lasers

1.6-1.7 mu m highly strained InGaAs/InGaAsP distributed feedback lasers was grown and fabricated by low pressure mentalorganic chemical vapor deposition. High quality highly strained InGaAs/InP materials were obtained by using strain buffer layer. Four pairs of highly strained quantum wells were used in the devices and carrier blocking layer was used to improve the temperature characteristics of the devices. The uncoated 1.66 mu m and 1.74 mu m lasers with ridge wave guide 3 mu m wide have low threshold current (< 15mA) and high output power (> 14mW at 100mA). In the temperature range from 10 degrees C to 40 degrees C, the characteristic temperature T-0 of the 1.74 mu m laser is 57K, which is comparable to that of the 1.55 mu m-wavelength InGaAsP/InP-DFB laser.

Design of two-dimensional photonic crystal edge emitting laser for photonic integrated circuits

An edge emitting laser based on two-dimensional photonic crystal slabs is proposed. The device consists of a square lattice microcavity, which is composed of two structures with the same period but different radius of air-holes, and a waveguide. In the cavity, laser resonance in the inner structure benelits from not only the anomalous dispersion characteristic of the first band-edge at the M point in the first Brillouin-zone but also zero photon states in the outer structure. A line defect waveguide is introduced in the outer structure for extracting photons from the inner cavity. Three-dimensional finite-difference time-domain simulations apparently show the in-plane laser output from the waveguide. The microcavity has an effective mode volume of about 3.2(lambda/eta(slab))(3) for oscillation -mode and the quality factor of the device including line defect waveguide is estimated to be as high as 1300.

Tunable Fano resonance in photonic crystal slabs

A three dimensional analysis of a special class of anisotropic materials is presented. We introduce an extension of the Scattering Matrix Method (SMM) to investigate the behavior of anisotropic Photonic Crystal Slabs (PhCS) subject to external radiation. We show how the Fano effect can play a fundamental role in the realization of tunable optical devices. Moreover, we show how to utilize electron injection, electric field and temperature as parameters to control the Fano resonance shift in both isotropic and anisotropic materials as Si and Potassium Titanium Oxide Phosphate (KTP). We will see that because Fano modes are sensitive and controllable, a broad range of applications can be considered. (c) 2006 Optical Society of America

Thermal lensing effect in ridge structure InGaN multiple quantum well laser diodes

Time-resolved light-current curves, spectra, and far-field distributions of ridge structure InGaN multiple quantum well laser diodes grown on sapphire substrate are measured with a temporal resolution of 0.1 ns under a pulsed current condition. Results show that the thermal lensing effect clearly improves the confinement of the higher order modes. The thermal lens leads to a lower threshold current for the higher order modes, a higher slope efficiency, and a change in the lasing mode of the device. The threshold current for the higher modes decreases by about 5 mA in every 10 ns in a pulse, and the slope efficiency increases by 7.5 times on the average when higher modes lase. (c) 2006 American Institute of Physics.

A 2x2 optical switch based on plasma dispersion effect in silicon-on-insulator

Based on Mach-Zehnder interferometer (MZI) structure, a 2 x 2 optical switch is fabricated on SOI wafer. Modulation of the refractive index of MZI arms is achieved through free carriers plasma dispersion effect of silicon. The device presents an insertion loss as low as 3.44 dB and a response time as small as 300 ns. The crosstalk and extinction ratio are -15.54 and 14.9 dB, respectively. Detailed analysis and explanation of the operating behaviors are also presented. (C) 2005 Elsevier B.V. All rights reserved.

Mach-Zehnder interferometers with asymmetric modulation arms in applications of high speed silicon-on-insulator based optical switches

Modulation arms with different widths are introduced to Mach-Zehnder interferometers (MZIs) to obtain improved performance. Theoretical analysis and numerical simulation have shown that when the widths of the two arms are properly designed to achieve an inherent m pi/2 (m is an odd integer) optical phase difference between the arms, the asymmetric MZI presents higher modulation speed. Furthermore, the carrier-absorption induced divergence of insertion losses in silicon-on-insulator (SOI) based MZI optical switches can be obviously improved.

Mode characteristics for equilateral triangle optical resonators

Mode characteristics of equilateral triangle resonators (ETRs) are analyzed based on the symmetry operation of the point group C-3v. The results show that doubly degenerate eigenstates can be reduced to the A(1) and A(2) representations of C-3v, if the longitudinal mode number is a multiple of 6; otherwise, they form the E irreducible representation Of C-3v. And the one-period length for the mode light ray is half of the perimeter of the ETR. Mode Q-factors are calculated by the finite-difference time-domain (FDTD) technique and compared with those calculated from far-field emission based on the analytical near-field pattern for TE and TM modes. The results show that the far-field emission based on the analytical field distribution can be used to estimate the mode Q-factor, especially for TM modes. FDTD numerical results also show that Q-factor of TE modes reaches maximum value as the longitudinal mode number is a multiple of 7. In addition, photoluminescence spectra and measured Q-factors are presented for fabricated ETR with side lengths of 20 and 30 mu m, and the mode wavelength intervals are compared with the analytical results.

Improving response speed of electrooptical switch in silicon-on-insulator by modifying modulation area structure

This paper reports on the simulation of two 2 x 2 electrooptical switches with different modulation area structures in silicon-on-insulator (SOI). A two-dimensional (2D) semiconductor device simulation tool PISCES-II has been used to analyze the dc and transient behaviors of the two devices. The modeling results show that the switch with an N+-I-P+-I-N+ modulation structure has a much faster response speed than the device with a P+-I-N+ modulation structure, although the former requires slightly stronger injection power.