Guoyang Xu

Organic electro-optic modulator using transparent conducting oxides as electrodes

A novel organic electro-optic (EO) modulator using transparent conducting oxides (ZnO and In2O3) as electrodes is demonstrated for the first time. The modulator employs the poled guest-host chromophore/polymer material AJL8/APC having r33=35pm/V and is able to achieve a low Vpi=2.8 V switching voltage for an 8mm-long device at a wavelength of 1.31ìm. This corresponds to a Vpi=1.1 V switching voltage for a 1cm-long device in a push-pull configuration. The push-pull VpiL figure of merit normalized for the EO coefficient is thus 1.1V-cm/(35pm/V), which is 3-4x lower than that can be achieved with a convetional modulator structure. The bottom electrode is ZnO grown by Metal-Organic Vapor Deposition (MOCVD) and top electrode In2O3 deposited using ionbeam assisted deposition. The top electrode is directly deposited on the guest-host organic material. The design and fabrication considerations for the modulator are also discussed.

An Ultracompact Optical Mode Order Converter

We describe the design and fabrication of an ultracompact optical mode order converter employing submicron waveguides. The mode converter can realize optical mode conversion between zeroth- and first-order optical modes with a device footprint less than 18 mum by 3 mum. The optical mode converter could be employed in various types of photonic integrated circuits where optical mode order conversion is needed

Low-voltage organic electro-optic modulators using transparent conducting oxides as electrodes

In this paper, we present a novel device structure for organic electro-optic modulators using transparent conducting oxides (TCOs) as electrodes to substantially reduce the switching voltage, and describe their fabrication. We report two different types of device geometry, a top conducting and a side conducting geometry, and discuss their strengths and weaknesses. We discuss how the voltage and speed performance of such modulators are dependant on the conductivity/optical loss ratio of the TCO electrodes. Our device simulation shows that by appropriately engineering the high TCO conductivity/optical loss ratio, 4-6x lower switching voltage can be achieved while still maintaining high modulation frequencies and low optical loss. We show that certain new TCO materials are capable of achieving the high conductivity/optical loss required for efficient modulation in the 1300-1550 nm wavelength range. We summarize the optical loss characteristics at 1300 nm of different types of thin-film TCO materials grown using different deposition techniques. TCO electrodes based on different types of materials, such as In2O3, ZnO, and ITO have been investigated for our device structures. Fabrication issues associated with the deposition of TCO electrodes directly on organic EO materials and our approach to addressing them are discussed. Initial results for organic EO modulators fabricated with TCOs as electrodes are presented, and the performance of these modulators are compared with theoretical modeling results. The new device structures presented here will enable next generation low-voltage organic EO modulators targeting RF photonics applications.

Quantum well saturation in ultra short absorptive waveguide section formed by quantum well intermixing

We demonstrate the fabrication of ultra-short absorptive sections in strongly confined waveguide employing quantum well intermixing technique, which could lead to the realization of nanoscale waveguides with selective saturable area for nonlinear optical device applications.

Low-voltage electro-optic modulator structure using transparent conducting oxide with high conductivity-loss ratio as electrodes

We describe a novel design of electro-optical modulator using transparent conducting oxide (TCO) with high /spl sigma///spl alpha/ ratio as electrode. We show that by engineering TCOs /spl sigma///spl alpha/ ratio, both low voltage and high-speed can be achieved.