Duk-Jun Kim

Temperature Dependence of Silicon Nanophotonic Ring Resonator With a Polymeric Overlayer

In this paper, we investigate the temperature dependence of a silicon-on-insulator-based silicon nanophotonic ring resonator covered with a polymeric overlayer. Temperature-dependent wavelength shift is measured to be as low as 5 pm/degC for the TM mode in a silicon ring resonator composed of a 500 times 220 nm2 channel waveguide. We also show through simulations and experiments that the temperature dependence can be reduced for the TE mode or for both the TE and TM modes by adjusting the mode volume of a silicon nanophotonic waveguide.

Controlling temperature dependence of silicon waveguide using slot structure.

We show that the temperature dependence of a silicon waveguide can be controlled well by using a slot waveguide structure filled with a polymer material. Without a slot, the amount of temperature-dependent wavelength shift for TE mode of a silicon waveguide ring resonator is very slightly reduced from 77 pm/ degrees C to 66 pm/ degrees C by using a polymer (WIR30-490) upper cladding instead of air upper cladding. With a slot filled with the same polymer, however, the reduction of the temperature dependence is improved by a pronounced amount and can be controlled down to -2 pm/ degrees C by adjusting several variables of the slot structure, such as the width of the slot between the pair of silicon wires, the width of the silicon wire pair, and the height of the silicon slab in our experiment. This measurement proves that a reduction in temperature dependence can be improved about 8 times more by using the slot structure.

Channel estimation and synchronization for polarization-division multiplexed CO-OFDM using subcarrier/polarization interleaved training symbols.

We propose and demonstrate the use of subcarrier/polarization-interleaved training symbols for channel estimation and synchronization in polarization-division multiplexed (PDM) coherent optical orthogonal frequency-division multiplexed (CO-OFDM) transmission. The principle, the computational efficiency, and the frequency-offset tolerance of the proposed method are described. We show that the use of subcarrier/polarization interleaving doubles the tolerance to the frequency offset between the transmit laser and the receivers optical local oscillator as compared to conventional schemes. Using this method, we demonstrate 43-Gb/s PDM CO-OFDM transmission with 16-QAM subcarrier modulation over 5,200-km of ultra-large-area fiber.

Suppression of temperature and polarization dependence by polymer overcladding in silica-based AWG multiplexer

A temperature and polarization-insensitive arrayed waveguide grating (AWG) multiplexer was realized by forming a polymer overcladding with negative thermo-optic coefficient on the silica core and undercladding without deteriorating the loss and crosstalk characteristics of the original silica AWG multiplexer.

Crosstalk reduction of silicon nanowire AWG with shallow-etched grating arms

The grating arms composed of silicon nanowires were shallow-etched to reduce the random phase error caused by the core width fluctuation. A fairly improved crosstalk value of 18 dB was achieved in the arrayed-waveguide grating with the on-chip loss of 3 dB.

RFID tag antenna mountable on metallic surfaces and matching method by parasitic patches

A low cost novel antenna for radiofrequency identification (RFID) tags mountable on metallic surfaces has been proposed and implemented. The proposed antenna indicates not only an easy impedance matching method with various microchip impedances but also the ability to be mounted on metallic surfaces. In this paper, the folded dipole type tag antenna with two parasitism-patches is proposed. This allows control of both the real and imaginary parts of the antenna impedance to achieve conjugate matching with the various values of the microchip impedance.

Hybrid-integrated coherent receiver using silica-based planar lightwave circuit technology

A hybrid-integrated coherent receiver module has been achieved using flip-chip bonding technology, consisting of a silica-based 90°-hybrid planar lightwave circuit (PLC) platform, a spot-size converter integrated waveguide photodiode (SSC-WG-PD), and a dual-channel transimpedance amplifier (TIA). The receiver module shows error-free operation up to 40Gb/s and OSNR sensitivity of 11.5 dB for BER = 10−3 at 25 Gb/s.

Temperature-Insensitive Silicon Nano-Wire Ring Resonator

We present a silicon nano-wire ring resonator with a temperature-dependent wavelength shift as low as 0.006 nm/degC by adjusting the mode volume of a SOl-based silicon waveguide covered with a polymeric material.

InP-based vertical dual-waveguide fiber-coupling structure

An InP-based fiber-coupling structure in which additional waveguide is overlaid on deep-ridge main waveguide is proposed with design and fabrication results. It is a feature of the structure that both the overlying and main waveguides participate in the fiber coupling.

Hybrid-integrated coherent receiver using silica-based PLC technology

We present a hybrid-integrated coherent receiver module using flip-chip technology for coupling a silica-based 90o-hybird planar lightwave circuit (PLC) chip to a spot-size converter integrated waveguide photodiode (SSC-WG-PD) array chip for a balanced photodiode (BPD) and interconnecting with a dual-channel transimpedance amplifier (TIA).