Zhenggang Lian

The optical properties of chalcogenide glasses: From measurement to electromagnetic simulation tools

Chalcogenide glasses are promising candidate materials for a wide range of photonics applications. The design and realisation of optical components based on these materials requires detailed information on their optical properties, frequently over a range of wavelengths. In this paper we review experimental refractive index data for three chalcogenide glass compositions, and discuss how various numerical fits to the data prove useful within electromagnetic simulation tools.

Switchable and tunable erbium-doped fiber lasers using a hollow-core Bragg fiber

A switchable and tunable erbium-doped fiber laser (EDFL) is proposed and experimentally demonstrated in this paper. A novel comb filter, which consists of a section of hollow-core Bragg fiber cascaded with Sagnac loop based on a polarization-maintaining fiber (PMF), is developed to suppress the mode competition in the EDFL. By carefully adjusting the polarization controllers, switchable and tunable single- or dual-wavelength lasing outputs with side-mode suppression ratios as high as 50 dB can be achieved. Single-wavelength lasing outputs with a 3 dB linewidth of 0.02 nm can be tuned within the wavelength range from 1562.4 nm to 1565.8 nm. Two kinds of dual-wavelength lasing outputs with different wavelength intervals of 1 nm and 2.1 nm can be obtained and the corresponding tunable wavelength range is 0.5 nm. Moreover, the wavelength shift and peak power fluctuation of both the single- and dual-wavelength lasing outputs are less than 0.1 nm and 2 dB over half an hour at room temperature, which indicates that the proposed fiber laser has good stability. To the best of our knowledge, it is the first time that a hollow-core Bragg fiber has been used as a comb filter in the EDFL.

Ultrabroadband polarization splitter based on three-core photonic crystal fiber with a modulation core.

We design an ultrabroadband polarization splitter based on three-core photonic crystal fiber (PCF). A modulation core and two fluorine-doped cores are introduced to achieve an ultrawide bandwidth. The properties of three-core PCF are modeled by using the full-vector finite element method along with the full-vector beam propagation method. Numerical results demonstrate that an ultrabroadband splitter with 320 nm bandwidth with an extinction ratio as low as -20  dB can be achieved by using 52.8 mm long three-core PCF. This splitter also has high compatibility with standard single-mode fibers as the input and output ports due to low splicing loss of 0.02 dB. All the air holes in the proposed structure are circular holes and arranged in a triangular lattice that makes it easy to fabricate.

Tunable dual-wavelength Erbium-doped fiber lasers using a hollow core Bragg fiber

A tunable dual-wavelength Erbium-doped fiber laser with a side mode suppression ratio of 50 dB is proposed. With the introduction of a hollow core Bragg fiber, the side modes can be effectively suppressed.

Review: Tg - reversible glass door to fabrication of photonic devices and integrated circuits

We review our development of sub-micron hot embossing or imprinting of glasses. We suggest that this is an emerging technology which shows great promise for the fabrication of glass photonic integrated circuits (PICs). The approach makes use of Tg (the glass transition) which gives inorganic compound glasses a key advantage over crystalline materials for fabricating photonic devices and PICs. Thus, when a glass is heated above Tg, the glass transforms to a supercooled liquid which may be shaped e.g. moulded. Cooling back down through Tg allows the shaping to be retained in the glassy state at room temperature. In this way, glasses may be shaped from the macro-scale e.g. to make light-refracting lenses down to the nano-scale e.g. for waveguides or photonic crystal arrays for dispersion management. Hence Tg is a reversible door to making photonic devices. This claim is illustrated by reviewing our recent work on hot embossing of inorganic compound glasses to make waveguides. Opportunities and potential pitfalls are highlighted. The background understanding of glass science underpinning the hot embossing methodology is presented.

T g : The glass door to photonic devices and integrated circuits

An emerging technology which shows promise for the fabrication of glass photonic integrated circuits (PICs), is sub-micron-scale embossing or imprinting. This approach makes use of Tg (the glass transition) which gives inorganic compound glasses a key advantage over crystalline materials for fabricating photonic devices and PICs. Thus, on heating the glass above Tg the supercooled liquid temperature regime is accessed which enables shaping, e.g. moulding, to be carried out. Cooling back down through Tg allows the shaping to be retained in the glassy state. In this way, glasses may be shaped from the macro-scale e.g. to make light-refracting lenses down to the nano-scale e.g. for waveguides or photonic crystal arrays for dispersion management. Hence Tg is one door to making photonic devices. This claim will be illustrated by reviewing both the background methodology and our recent work on hot embossing of inorganic compound glasses to make waveguides. Opportunities and potential pitfalls will be highlighted.