后处理对离子交换磷酸盐玻璃平面光波导的影响

研究了退火和二次离子交换对Er^3＋／Yb^3＋共掺的磷酸盐玻璃平面光波导传输特性的影响。在退火过程中，由于热效应和波导层Ag^＋离子的浓度差使得Ag^＋离子重新分布；随着退火时间的延长和温度的升高，光波导模式数目逐渐增加，波导层深度加深，且波导表面折射率与玻璃基质折射率差减小，退火扩散深度与退火时间的平方根成正比。电子探针结果显示在二次离子交换后形成了掩埋式的光波导，Ag^＋离子浓度接近二次方分布，而掩埋式的光波导有助于降低光波导的传输损耗。

Broadband infrared luminescence of bismuth-doped borosilicate glasses

We prepare bismuth-doped borosilicate glasses and the luminescence properties in infrared wavelength region are investigated. Transmission spectrum, fluorescence spectrum and fluorescence decay curve are measured. The glasses exhibit a broad infrared luminescence peaking at 1340nm with the full width at half maximum of about 205nm, and lifetime of 273 mu s when excited by an 808-nm laser diode. The glasses are promising materials for broadband optical amplifiers and tunable lasers.

超宽带光纤放大器用的新型掺铋发光材料

最近，一种新型的掺铋发光材料引起了人们的关注。这种发光材料有长的荧光寿命（τ＞200μs），在800nm激光激发下发射波长在1200～1600nm区间的超宽带荧光（荧光半高宽FWHM＞200nm），其发光性质与以往文献中报道的Bi^3＋或Bi^2＋掺杂的发光材料的性质截然不同；光发射截面（σem）是光掺铒光纤放大器玻璃（EDFAG）的2～3倍，其σem×FWHM值是EDFAG的10倍左右，σem×τ值是掺Ti^3＋蓝宝石的3倍左右。

High quantum efficiency and high concentration erbium-doped silica glasses fabricated by sintering nanoporous glasses

A new method was used to prepare erbium-doped high silica (SiO2% > 96%) glasses by sintering nanoporous glasses. The concentration of erbium ions in high silica glasses can be considerably more than that in silica glasses prepared by using conventional methods. The fluorescence of 1532 nm has an FWHM (Full Wave at Half Maximum) of 50 nm, wider than 35 nm of EDSFA (erbium-doped silica fiber amplifer), and hence the glass possesses potential application in broadband fiber amplifiers. The Judd-Ofelt theoretical analysis reflects that the quantum efficiency of this erbium-doped glass is about 0.78, although the erbium concentration in this glass (6 x 103) is about twenty times higher than that in silica glass. These excellent characteristics of Er-doped high silica glass will be conducive to its usage in optical amplifiers and microchip lasers.

Intense upconversion and infrared emissions in Er3+;Yb3+ codoped Lu2 Si O5 and (Lu0.5 Gd0.5)2 Si O5 crystals

High optical quality Lu2SiO5 (LSO) and (Lu0.5Gd0.5)(2)SiO5 (LGSO) laser crystals codoped with Er3+ and Yb3+ have been fabricated by the Czochralski method. Intense upconversion (UC) and infrared emission (1543 nm) are observed under excitation of 975 nm. The luminescence processes are explained and the emission efficiencies are quantitatively obtained by measuring the UC efficiency and calculating the emission cross section. The temperature-dependent optical properties of the crystals are also investigated. Our study indicates that Er3+-Yb3+ : LSO and Er3+-Yb3+: LGSO crystals are promising gain media for developing the solid-state 1.5 mu m optical amplifiers and tunable UC lasers. (c) 2008 American Institute of Physics.

Noise suppression in monolithically integrated Michelson interferometer

A novel monolithically integrated Michelson interferometer using intersecting twin-contact semiconductor optical amplifiers is proposed and implemented whereby the two arms are gain imbalanced to give enhanced noise suppression. Experimental OSNR improvements of 8.4 dB for pulses with durations 8 ps and by default ER of 14 dB are demonstrated for low driving currents of between 25 and 30 mA. This is believed to be the smallest Michelson interferometer to date.

Recent progress in high-bit-rate applications of four-wave-mixing in SOAs

Non-linearities in semiconductor optical amplifiers have been used to demonstrate a wide range of functions applicable to future optical networks such as wavelength conversion and optical switching. Four-wave-mixing effects in SOAs have been studied extensively in many laboratories with respect to the underlying physical processes and system applications. At BT Labs an optimization of SOAs for FWM has been achieved by altering the device active layer composition and by increasing the device length. We will review recent progress at BT Labs in dispersion compensation, wavelength conversion and demultiplexing at bit-rates of 40 Gbit/s using these devices.

Recent progress in high-bit-rate applications of four-wave-mixing in SOAs

Non-linearities in semiconductor optical amplifiers have been used to demonstrate a wide range of functions applicable to future optical networks such as wavelength conversion and optical switching. Four-wave-mixing effects in SOAs have been studied extensively in many laboratories with respect to the underlying physical processes and system applications. At BT Labs an optimisation of SOAs for FWM has been achieved by altering the device active layer composition and by increasing the device length. We will review recent progress at BT Labs in dispersion compensation, wavelength conversion and demultiplexing at bit-rates of 40Gbit/s using these devices.

Light-matter interaction in a microcavity-controlled graphene transistor

Graphene has extraordinary electronic and optical properties and holds great promise for applications in photonics and optoelectronics. Demonstrations including high-speed photodetectors, optical modulators, plasmonic devices, and ultrafast lasers have now been reported. More advanced device concepts would involve photonic elements such as cavities to control light-matter interaction in graphene. Here we report the first monolithic integration of a graphene transistor and a planar, optical microcavity. We find that the microcavity-induced optical confinement controls the efficiency and spectral selection of photocurrent generation in the integrated graphene device. A twenty-fold enhancement of photocurrent is demonstrated. The optical cavity also determines the spectral properties of the electrically excited thermal radiation of graphene. Most interestingly, we find that the cavity confinement modifies the electrical transport characteristics of the integrated graphene transistor. Our experimental approach opens up a route towards cavity-quantum electrodynamics on the nanometre scale with graphene as a current-carrying intra-cavity medium of atomic thickness. © 2012 Macmillan Publishers Limited. All rights reserved.

Energy transfer and enhanced 1.54 μm emission in Erbium-Ytterbium disilicate thin films.

α-(Yb1-xErx)2Si2O7 thin films on Si substrates were synthesized by magnetron co-sputtering. The optical emission from Er3+ ions has been extensively investigated, evidencing the very efficient role of Yb-Er coupling. The energy-transfer coefficient was evaluated for an extended range of Er content (between 0.2 and 16.5 at.%) reaching a maximum value of 2 × 10⁻¹⁶ cm⁻³s⁻¹. The highest photoluminescence emission at 1535 nm is obtained as a result of the best compromise between the number of Yb donors (16.4 at.%) and Er acceptors (1.6 at.%), for which a high population of the first excited state is reached. These results are very promising for the realization of 1.54 μm optical amplifiers on a Si platform.

Scalable, low-energy hybrid photonic space switch

A scalable monolithically integrated photonic space switch is proposed which uses a combination of Mach-Zehnder modulators and semiconductor optical amplifiers (SOAs) for improved crosstalk performance and reduced switch loss. This architecture enables the design of high-capacity, high-speed, large-port count, low-energy switches. Extremely low crosstalk of better than -50 dB can be achieved using a 2 × 2 dilated hybrid switch module. A 'building block' approach is applied to make large port count optical switches possible. Detailed physical layer multiwavelength simulations are used to investigate the viability of a 64 × 64 port switch. Optical signal degradation is estimated as a function of switch size and waveguide induced crosstalk. A comparison between hybrid and SOA switching fabrics highlights the power-efficient, high-performance nature of the hybrid switch design, which consumes less than one-third of the energy of an equivalent SOA-based switch. The significantly reduced impairments resulting from this switch design enable scaling of the port count, compared to conventional SOA-based switches. © 1983-2012 IEEE.

Monolithic MZI-SOA hybrid switch for low-power and low-penalty operation.

We report the first experimental demonstration of a monolithically integrated hybrid dilated 2×2 modular optical switch using Mach-Zehnder modulators as low-loss 1×2 switching elements and short semiconductor optical amplifiers to provide additional extinction and gain. An excellent 40 dB cross-talk/extinction ratio is recorded with data-modulated signal-to-noise ratios of up to 44 dB in a 0.1 nm bandwidth. A switching time of 3 ns is demonstrated. Bit error rate studies show extremely low subsystem penalties of less than 0.1 dB, and studies indicate that, by using this hybrid switch building block, an 8×8 port switch could be achieved with 14 dB input power dynamic range for subsystem penalties of less than 0.5 dB.

Noise suppression in a novel monolithically integrated michelson interferometer

A novel monolithically integrated Michelson Interferometer using intersecting twincontact semiconductor optical amplifiers is proposed whereby the two arms are gain imbalanced to give noise suppression. Experimental OSNR improvements of 6.2dB for 8ps pulses is demonstrated. © 2005 Optical Society of America.

Noise suppression in a novel monolithically integrated michelson interferometer

A novel monolithically integrated Michelson Interferometer using intersecting twincontact semiconductor optical amplifiers is proposed whereby the two arms are gain imbalanced to give noise suppression. Experimental OSNR improvements of 6.2dB for 8ps pulses is demonstrated. © 2005 Optical Society of America.

A new method of restraining the Fabry-Perot resonance

In the paper, we present a new method of restraining the Fabry-Perot resonance. The method is to combine dip angle with taper angle in the structure of the device and avoids the process of antireflection coatings. The experimental results show that restraining effect is apparent. A high threshold current has been obtained for the sample with both dip angle and taper angle structure. It provides a new method to make traveling-wave optical amplifiers.