Yu Jinzhong

Sputtered AIN films for semiconductor lasers

Abstract The deposition rates and properties of AIN films produced by r.f. sputter deposition are dependent on the discharge mixture pressure, discharge voltage and depositing time. The breakdown electric field of the AIN films can range from 3.6×10 6 to 9.1×10 6 V cm − . These films have been successfully used as a new dielectric facet reflector and protector for 850 nm GaAs/GaAlAs double-heterostructure lasers. A 1300 nm InGaAsP/InP heterostructure laser with a double-channel ridge waveguide structure was successfully made by the deposition of an AIN film as the passivating layer. The data for AIN, Al 2 O 3 , SiO 2 , Si 3 N 4 , GaAs and InP were compared, and AIN is the best of these in the field of semiconductor optoelectronic devices on a substrate of GaAs or InP.

High-speed 2 £ 2 silicon-based electro-optic switch with nanosecond switch time ⁄

A 2 £ 2 electro-optic switch is experimentally demonstrated using the optical structure of a Mach{Zehnder interferometer (MZI) based on a submicron rib waveguide and the electrical structure of a PIN diode on silicon-on-insulator (SOI). The switch behaviour is achieved through the plasma dispersion efiect of silicon. The device has a modulation arm of 1 mm in length and cross-section of 400 nm£340 nm. The measurement results show that the switch has a V…L… flgure of merit of 0.145 V¢cm and the extinction ratios of two output ports and cross talk are 40 dB, 28 dB and i28 dB, respectively. A 3 dB modulation bandwidth of 90 MHz and a switch time of 6.8 ns for the rise edge and 2.7 ns for the fall edge are also demonstrated.

Design, fabrication and characterization of a high-performance microring resonator in silicon-on-insulator

A high-performance microring resonator in a silicon-on-insulator rib waveguide is realized by using the electron beam lithography followed by inductively coupled plasma etching. The design and the experimental realization of this device are presented in detail. In addition to improving relevant processes to minimize propagation loss, the coupling efficiency between the ring and the bus is carefully chosen to approach a critical coupling for high performance operating. We have measured a quality factor of 21,200 and an extinction ratio of 12.5dB at a resonant wavelength of 1549.32nm. Meanwhile, a low propagation loss of 0.89dB/mm in a curved waveguide with a bending radius of 40/?m is demonstrated as well.

High-speed and broad optical bandwidth silicon modulator

The Chern number is often used to distinguish between different topological phases of matter in two-dimensional electron systems. A fast and efficient coupling-matrix method is designed to calculate the Chern number in finite crystalline and disordered systems. To show its effectiveness, we apply the approach to the Haldane model and the lattice Hofstadter model, the quantized Chern numbers being correctly obtained. The disorder-induced topological phase transition is well reproduced, when the disorder strength is increased beyond the critical value. We expect the method to be widely applicable to the study of topological quantum numbers.A high-speed silicon modulator with broad optical bandwidth is proposed based on a symmetrically configured Mach—Zehnder interferometer. Careful phase bias control and traveling-wave design are used to improve the high-speed performance. Over a broadband wavelength range, high-speed operation up to 30 Gbit/s with a 4.5 dB–5.5 dB extinction ratio is experimentally demonstrated with a low driving voltage of 3 V.

Modelling and analysis of modal behaviour in SOI slot waveguides

Mode behaviour for SOI slot waveguides is modelled and analysed using a numerical full vectorial method based on the film mode matching method (MMM). Only the quasi-TE mode is investigated. Waveguide heights and slot widths, as well as silicon widths are properly chosen with respect to the single mode behaviour in the slot region. Comparison between the effective index method and our side loss method shows that our single mode condition is creditable. The optical power confinement in slot region for the quasi-TE mode is also studied and presented. We demonstrate that the maximum achievable optical power confinement P-slot and the maximum normalized average optical intensity I-slot are 42% and 26 mu m(-2), respectively.

Fabrication of thermo-optic switch in silicon-on-insulator

Silicon-on-insulator technology has been used to fabricate 2 x 2 thermo-optic switches. The switch shows crosstalk of -23.4 dB and extinction ratio of 18.1 dB in the bar-state. The switching speed is less than 30 mus and the power consumption is about 420 mW The measured excess loss is 1.8 dB. These merits make the switch more attractive for applications in wavelength division multiplexing.

A comparison of silicon oxide and nitride as host matrices on the photoluminescence from Er3+ ions

This paper compares the properties of silicon oxide and nitride as host matrices for Er ions. Erbium-doped silicon nitride films were deposited by a plasma-enhanced chemical-vapour deposition system. After deposition, the films were implanted with Er3+ at different doses. Er-doped thermal grown silicon oxide films were prepared at the same time as references. Photoluminescence features of Er3+ were inspected systematically. It is found that silicon nitride films are suitable for high concentration doping and the thermal quenching effect is not severe. However, a very high annealing temperature up to 1200 degrees C is needed to optically activate Er3+ which may be the main obstacle to impede the application of Er-doped silicon nitride.

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.

Near infrared photoluminescence from Yb,Al Co-implanted SiO2 films on silicon

Intense room-temperature near infrared (NIR) photoluminescence (980 nm and 1032 nm) is observed from Yb,Al co-implanted SiO2 films on silicon. The optical transitions occur between the F-2(5/2) and F-2(7/2) levels of Yb3+ in SiO2. The additional Al-implantation into SiO2 films can effectively improve the concentration quenching effect of Yb3+ in SiO2. Photoluminescence exitation sprectroscopy shows that the NIR photoluminescence is due to the non-radiative energy transfer from Al-implantation-induced non-bridging oxygen hole defects in SiO2 to Yb3+ in the Yb-related luminescent complexes. It is believed that the defect-mediated luminscence of rare-earth ions in SiO2 is very effective.

Structural optimizations of SOI-based single-mode rib waveguide bends [optical waveguides]

The effects of structure parameters on the bend loss of rib silicon-on-insulator (SOI) bend waveguides have been analyzed by means of the effective index method (EIM) and 2D bend loss formula. The simulation results indicate that the bend loss decreases with an increase of bend radius and waveguide width, as well as with a decrease of the step factor of the rib waveguide. Moreover, the optimal structure parameters have been found when the bend waveguides are single-mode.