Cylindrical concave diffraction grating utilising thin silicon chip

A unique manufacturing method for concave diffraction gratings is proposed. Also, a cylindrical concave diffraction grating was manufactured with a multimode slab waveguide. A silicon plane diffraction grating was bent cylindrically in this method. The efficiency of the concave diffraction grating was 82% at a 1.3 ?m wavelength. The efficiency was about the same as that of the plane diffraction grating.     

Semiconductor monolithic wavelength selective router using agrating switch integrated with a directional coupler

A semiconductor monolithic wavelength selective router is proposed. An electrically tunable grating switch is monolithically integrated with a directional coupler. The effect of sidelobe on the demultiplexing characteristics of the router is investigated, and it is shown that the sidelobes degrade the wavelength crosstalk and introduce a power penalty for demultiplexing characteristics. A phase-synchronized sampled grating is introduced to suppress the sidelobes, and wavelength router switching is observed in this structure. The extinction ratio is over 10 dB at a current injection of 25 mA. Using this structure, power-penalty-free wavelength selective routing at a 2.5 Gb/s wavelength-division-multiplexed NRZ random pattern is demonstrated     

Chirping of the waveguide grating router for free-spectral-range mode selection in the multifrequency laser

Because the transmission through each input-output combination of a conventional waveguide grating router consists of a periodic sequence of equal-height passbands spaced by the router free spectral range, the absolute laser oscillation wavelength and single-passband oscillation can be difficult to control for all the channels in the multifrequency waveguide grating router laser. However, the router can be designed to have one dominant passband, with the neighboring passbands experiencing lower transmission coefficients for all the input output combinations by means of chirping of the waveguide grating. Such chirping is discussed theoretically and is demonstrated experimentally.     

用于平场光谱仪的非球面全息凹面光栅设计

基于全息凹面光栅理论和ZEMAX软件,设计了一种用于平场光谱仪的消象差平场非球面全息凹面光栅。与采用相同口径、相同相对孔径的全息凹球面光栅构成的平场光谱仪比较,在入射狭缝宽度相同的情况下,该光栅所构成的平场光谱仪的分辨率得到明显提高。同时,利用较大相对孔径非球面全息凹面光栅,可使平场光谱仪的结构更紧凑,从而可实现平场光谱仪的小型化。     

Design and analysis of spectral beam combining system for fiber lasers based on a concave grating

A novel fiber laser spectral beam combining scheme based on a concave grating is presented.The principle of the presented system is analyzed,and a concave grating with blazed structure for spectral beam combining is designed.The combining potential of the system is analyzed,and the results show that 39 Yb-doped fiber laser can be spectrally beam combined via the designed system.By using scalar diffraction theory,the combining effect of the system is analyzed.The results show that the diffraction efficiency of the designed concave grating is higher than 72% over the whole gain bandwidth,and the combining efficiency is 73.4%.With output power of 1 kW for individual fiber laser,combined power of 28.6 kW can be achieved.     

Analysis of relative intensity noise in tapered grating QWS-DFB laser diodes by using three rate equations model

The relative intensity noise (RIN) of quarter wavelength shift distributed feedback (QWS-DFB) laser diodes is analyzed theoretically for tapered grating structures. Tapered grating structures can reduce spatial hole burning (SHB) effect in QWS-DFB lasers. Two types of tapered, concave and convex grating are introduced. According to the results concave tapered grating structures have lower flatness parameter relative to convex and uniform grating. Numerical analysis shows that concave tapered grating structures, in spite of lower SHB effect, have larger RIN for some values of grating parameters. In concave and convex structures, with increasing the concavity and convexity of grating, mean value of RIN in the frequency range 5–500 MHz reduces. RIN spectrum calculations have been done by three rate equations model and transfer matrix method.     

面向定向能应用的光纤激光谱组束系统设计

针对定向能激光武器系统对结构紧凑的高功率、高质量光纤激光源的需求,提出了一种新颖的基于凹面光栅的光纤激光谱组束方案。该系统可将组束激光直接聚焦到目标点,且可以根据目标点位置的不同,通过对各组束阵元输出端位置的实时调整,实现对目标的灵活跟踪。分析了基于凹面光栅光纤激光谱组束系统的工作原理,设计了用于组束的闪耀光栅结构的凹面光栅,阐述了系统实现目标跟踪的原理。根据目标点位置的不同,通过调整系统状态,可使该系统适应不同目标距离的应用需求,非常适于激光定向能系统应用。     

Improved Waveguide Grating Router Suitable for Local Access in Optical Networks

An improved waveguide grating router suitable for local access and metropolitan applications is proposed. By using a bidirectional design, 16 channels widely spaced by 1250 GHz can be transmitted in each direction, with router loss close to 3 dB. The router can be used outdoors without temperature control and, because of the large channel spacing, the tolerances on the laser wavelengths are substantially reduced.     

All-fiber active add-drop wavelength router

We describe a fiber Bragg grating Mach-Zehnder interferometer (FBG-MZI) which utilizes active phase control. The active FBG-MZI is operated as a wavelength router, where the grating-selected wavelength channel can be actively routed. We believe this is the first demonstration of an all fibre FBG-MZI wavelength router.     

Demonstration of 9×200 Mbit/s wavelength division multiplexedtransmitter

A multifrequency laser capable of generating 200 Mbit/s data rates simultaneously at nine different wavelengths is demonstrated. The laser is based on the monolithic integration of a waveguide grating router with semiconductor optical amplifiers and thus provides automatic alignment of the optical channel wavelengths. This multifrequency laser may have important applications for local access WDM networks     

Wavelength selectable laser with inherent wavelength andsingle-mode stability

We present a 8×200 GHz wavelength selectable laser that has inherent wavelength and single-longitudinal-mode stability. The wavelength stabilization is accomplished by the long cavity and passive intracavity chirped waveguide grating router, and the single-mode stabilization is accomplished by gain nonlinearities, aided by minimization of cavity length and router passband width     

Chirped waveguide grating router multifrequency laser with absolute wavelength control

We apply chirping of the waveguide grating router to the multifrequency laser (MFL). We present a 10/spl times/100 GHz chirped MFL that has precise absolute oscillation wavelength control and guaranteed single router free-spectral-range mode oscillation for all 10 channels and, additionally, guaranteed single cavity mode oscillation for 4 of the channels.     

A single WDM multi/demultiplexer for all SMF transmission windowsin 1280-1680 nm

A new advanced design methodology for multi/demultiplexers based on holographic concave gratings is presented. The proposed design is benchmarked against a single grating operating in the entire useful range of the single-mode fiber (1280-1680 nm). In addition, a new design for a grating serving as a 1000 wavelength-division-multiplexing channel demultiplexer within the 1450-1650 nm spectral range is given. It is shown that the new mount offers considerably improved performance     

基于牛顿迭代算法的凹面光栅优化设计

本文讨论了基于牛纯迭代算法的凹面光栅优化设计,它不同于传统的基于光程函数级数展开的设计思路,凹面光栅的结构通过两个由特殊设计要求选择的约束方程决定,光栅的刻槽位置可通过约束方程的数值求解得到,一般从选定的光栅顶点依次迭代求出。基于此方法讨论了无象差点结构凹面光栅的优化设计,并给出了数值模拟结果。关于此方法的进一步应用,其中包括不能通过光程函数法设计的例子,也做了初步的讨论。     

Quantitative Analysis of a Flat-Top Planar Waveguide Demultiplexer

A three-focal-point method is used for the design of a flat-top planar waveguide concave grating. With the Gaussian approximation a modified formula is proposed and is compared with the numerical model of the scalar diffraction theory by using a design example. The sources of loss caused by the flat-top design and the grating are taken into consideration. The optimal separation between the two outmost focal points is obtained and the spectral response of the demultiplexer with a ripple below 0.04 dB is achieved.     

A novel architecture of optical code label processing in parallel designed for all optical routing system

A novel architecture of optical code label routing is designed based on optical code division multiplexing techniques, which performs the data packet forwarding and processing in parallel with a way of making the label and payload encoded and decoded separately. It uses optical polarity characteristics to realize the separation of the label and payload, employs fiber Bragg grating to encode/decode the label and payload so as to process them in parallel, and makes the forwarding and routing process realized in the optical domain. In the core router, the separation of the label and payload guarantees that the switch processing only includes the short label code recognition, without processing the payload. The payload recognition is carried out in the edge router. Thus, the router can simplify the processing of encoding and decoding in the core router, accelerating the switching, and increase the throughput greatly. Moreover, the novel routing scheme not only supports the varying of data packets, transparent transmission, fine granularity switching, and so on, but also is suitable for the aggregation of data service. It is attractive for the future development of all optical routing.     

Packet-by-packet wavelength-routing interconnect technique for 5Tbit/s switching system

A packet-by-packet wavelength-routing interconnect technique for a 5 Tbit/s switching system with a three-stage architecture has been demonstrated. The technique uses an optical wavelength division multiplexing (WDM) link and dynamic bandwidth-sharing among wavelengths. The inter-stage, electro-optical interconnection subsystem was fabricated using very compact 2.5 Gbit/s, eight-wavelength WDM transmitters/receivers and an arrayed-waveguide grating router     

Optical cross-connect structures for interleaved multiwavelengthbidirectional ring networks

Novel bidirectional optical cross-connect structures using a single arrayed waveguide grating router and tunable fibre Bragg gratings have been proposed for interleaved multiwavelength ring networks. In the proposed structures, each wavelength channel is independently switched by tuning the centre wavelength of the gratings. The feasibility of the cross-connectors has been experimentally demonstrated. A homodyne crosstalk less than -26 dB and a backscattering suppression ratio of -35 dB have been obtained     

Compact and low-loss manner of waveguide grating router passbandflattening and demonstration in a 64-channel blocker/multiplexer

We present a compact design for flattening the passband of a waveguide grating router theoretically without excess loss or chromatic dispersion. We demonstrate its use in a 64-wavelength-channel blocker/multiplexer     

Double-chirping of the waveguide grating router

Although chirping only the arm lengths of the waveguide grating router allows each input-output port combination to have a dominant passband in one grating order with the peak transmissivities in other orders suppressed, all but one of the dominant passbands necessarily have reduced peak transmissivities and increased widths, and the extraneous grating order passband suppression is limited. We show here that simultaneously chirping both the arm lengths and the angular distribution of the arms in one of the star couplers eliminates these deficiencies.