Daru Chen

Cylindrical hybrid plasmonic waveguide for subwavelength confinement of light

A novel cylindrical hybrid plasmonic waveguide is proposed to achieve subwavelength confinement of light. With a metal core surrounded by a silica layer and a silicon layer, the proposed cylindrical hybrid plasmonic waveguide can achieve a ring-structure mode profile at the operating wavelength (1550 nm). Most mode power locates in the silica layer with a nanoscale thickness (e.g., 50, 20, or even 5 nm), which is due to the effects of both a strong discontinuity of the normal component of the electric field at the silicon-silica interface and the exited surface plasmon wave at the silica-metal interface. Cylindrical hybrid plasmonic waveguides with different structure parameters are investigated and a relatively long propagation distance of tens of micrometers (or even hundreds of micrometers) is observed.

Highly birefringent photonic crystal fiber based on a double-hole unit

We propose a novel highly birefringent photonic crystal fiber (PCF) based on a double-hole unit. Because of the effect of the double-hole unit in which double airholes can be effectively viewed as elliptical airholes, the proposed PCF can achieve birefringence similar to that of an elliptical-hole PCF with high birefringence even up to the order of 0.01 and still avoid the inherent challenge to fabricate an elliptical-hole PCF. The proposed PCF also has a lower confinement loss than an elliptical-hole PCF with the same air-filling fraction.

Switchable and tunable thulium-doped fiber laser incorporating a Sagnac loop mirror

A thulium-doped fiber laser employing a Sagnac loop mirror made by a 145.5 cm polarization-maintaining fiber is demonstrated, which can operate with stable dual-wavelength lasing or tunable single-wavelength lasing around 1860 nm. Both stable dual-wavelength and tunable single-wavelength lasing are achieved by adjusting a polarization controller in the Sagnac loop mirror. The experimental results show that the output of the reported fiber laser with two different operation modes is rather stable at room temperature.

Suspended hollow core fiber for terahertz wave guiding

A suspended hollow core fiber is proposed as a novel Terahertz waveguide with low loss property, and is investigated compared with a suspended solid core fiber.

Silicon hybrid plasmonic microring resonator for sensing applications.

A novel silicon hybrid plasmonic microring resonator consisting of a silver nanoring on top of a silicon-on-insulator ring is proposed and investigated theoretically for possible applications in sensing at the deep subwavelength scale. By using the finite-element method, insight into how the mode properties (Q factor, effective mode volume, energy ratio, sensitivity) depend on the geometric structure of the hybrid microring resonator is presented. Simulation results reveal that this kind of hybrid microcavity maintains a high Q factor ∼600, an ultrasmall mode volume of 0.15u2009u2009μm3, and high sensitivity of 497u2009u2009nm/refractive index unit for refractive index sensing. The hybrid plasmonic microcavity with optimized geometric structures presented provides the potential for ultracompact sensing applications.

Focusing of electromagnetic fields in high-Q hybrid wedge plasmon polariton microresonator.

We theoretically propose a hybrid microresonator consisting of a metallic wedge ring and a silica ring and investigate the existing whispering-gallery-like hybrid wedge plasmon polariton modes. These tightly confined hybrid plasmon modes are found to possess ultrasmall mode volumes while maintaining relatively high quality factors simultaneously at room temperature; that is, high values of Q/V are obtained. For example, a Purcell factor of 70 is achieved at the telecommunication wavelength of 1550 nm. This plasmon microresonator shows great potential in low-threshold plasmonic microlasers and cavity quantum electrodynamics.

Side-hole two-core microstructured optical fiber for hydrostatic pressure sensing.

A novel side-hole two-core microstructured optical fiber (STMOF) is proposed for hydrostatic pressure sensing. The two solid fiber cores are surrounded by a few small air holes and two large air holes, and are separated by one small air hole in the center of the cross section of the STMOF. The two large air holes that we called side holes essentially provide a built-in transducing mechanism to enhance the pressure-induced index change, which ensures the high sensitivity of the hydrostatic pressure sensor based on the STMOF. Mode coupling between the two fiber cores of the STMOF has been investigated, which provides a pressure-dependent transmission spectrum by injecting a broadband light into one fiber core of the STMOF on one side and detecting output spectrum on another fiber core on the other side. Our simulations show that there is a one-to-one correspondence between the hydrostatic pressure applied on the STMOF and the peak wavelength shift of the transmission spectrum. A hydrostatic pressure sensor based on an 8 cm STMOF has a sensitivity of 0.111 nm/Mpa for the measurement range from 0 Mpa to 200 Mpa. The performances of hydrostatic pressure sensors based on STMOFs with different structure parameters are presented.