We report the design and characterization of an InP-based coherent optical transmitter integrating optical gain together with modulator, monitor and control elements to provide enhanced performance for high spectral efficiency 100Gb/s transmission.

The origin of ultra-compact dwarfs (UCDs; r(h) greater than or similar to 10 pc)-objects larger and more massive than typical globular clusters (GCs), but more compact than typical dwarf galaxies-has been hotly debated in the 15 years since their discovery. Even whether UCDs should be considered galactic in origin, or simply the most extreme star clusters, is not yet settled. We present the dynamical properties of 97 spectroscopically confirmed UCDs and 911 GCs associated with the central cD galaxy of the Virgo cluster, M87. Our UCDs, of which 89% have M-* greater than or similar to 2x10(6) M-circle dot and 92% are as blue as the classic blue GCs, nearly triple the confirmed sample of Virgo UCDs, providing by far the best opportunity for studying global dynamics of a UCD system. We found that (1) UCDs have a surface number density profile that is shallower than that of blue GCs in the inner similar to 70 kpc and as steep as that of red GCs at larger radii; (2) UCDs exhibit a significantly stronger rotation than GCs, and blue GCs seem to have a velocity field that is more consistent with that of the surrounding dwarf ellipticals than with that of UCDs; (3) UCDs have an orbital anisotropy profile that is tangentially biased at radii less than or similar to 40 kpc and radially biased farther out, whereas blue GCs become more tangentially biased at larger radii beyond similar to 40 kpc; (4) GCs with M-* greater than or similar to 2 x 10(6) M-circle dot have rotational properties indistinguishable from the less massive ones, suggesting that it is the size, instead of mass, that differentiates UCDs from GCs as kinematically distinct populations. We conclude that most UCDs in M87 are not consistent with being merely the most luminous and extended examples of otherwise normal GCs. The radially biased orbital structure of UCDs at large radii is in general agreement with the "tidally threshed dwarf galaxy" scenario.

In this paper, a wavelength-division-multiplexing passive optical network (WDM-PON) system using small form-factor pluggable plus (SFP+) packaged full C-band tunable transceivers is demonstrated for the first time to our knowledge. Within the transceivers, a novel digital-supermode distributed Bragg reflector (DS-DBR) laser with a monolithically integrated Mach-Zehnder modulator is employed as the transmitter. A generic current control algorithm is used to drive the DS-DBR laser, which employs a laser current training sequence ensuring successful operation without the need for individual laser characterization. A pilot-tone-based feedback control loop is implemented using embedded hardware, which is able to lock the output wavelengths from three identical optical network units with less than +/-3 GHz deviation from their assigned channels. Error-free transmission is achieved at a 10 GbE data rate. With the feedback control loop running continuously, the system shows a sensitivity of -23 dBm for a bit error rate of 10(-12).

Photonic integrated circuits (PICs) are considered as the way to make photonic systems or subsystems cheap and ubiquitous. PICs still are several orders of magnitude more expensive than their microelectronic counterparts, which has restricted their application to a few niche markets. Recently, a novel approach in photonic integration is emerging which will reduce the R&D and prototyping costs and the throughput time of PICs by more than an order of magnitude. It will bring the application of PICs that integrate complex and advanced photonic functionality on a single chip within reach for a large number of small and larger companies and initiate a breakthrough in the application of Photonic ICs. The paper explains the concept of generic photonic integration technology using the technology developed by the COBRA research institute of TU Eindhoven as an example, and it describes the current status and prospects of generic InP-based integration technology.

In this article the operation of a novel, prototypical WDM-PON system with bi-directional data rates of up to 10.3 Gb/s is experimentally demonstrated. In the optical line terminal (OLT) a novel photonic integrated circuit (PIC) is deployed integrating an array of tunable lasers with Mach-Zehnder modulators and a star coupler. Wavelength control is achieved by a pilot-tone based scheme with a shared wavelength-locker (etalon). In the optical network unit (ONU) a novel Aluminium-containing laser is used, which has been specially designed for operation between 70deg C to 90deg C without requiring a thermo-electric cooler (TEC). For reduced cost and complexity the tunable laser is not equipped with an etalon. Instead it employs a generic contol algorithm, which is augmented by a pilot tone based scheme is used for centralized wavelength locking of all channels at the OLT.

We demonstrate automatic operation of a cooler-less tunable-laser based WDM-PON system. Using a pilot-tone based overhead channel and centralized wavelength locking scheme, 1 Gb/s and 10 Gb/s data transmission is demonstrated in a multi-user set-up.

We present spectroscopic observations of ultracompact dwarf (UCD) galaxies in the Fornax and Virgo clusters made to measure and compare their stellar populations. The spectra were obtained on the Gemini-North (Virgo) and Gemini-South (Fornax) telescopes using the respective Gemini Multi-Object Spectrographs. We estimated the ages, metallicities and abundances of the objects from measurements of Lick line-strength indices in the spectra; we also estimated the ages and metallicities independently using a direct spectral fitting technique. Both methods revealed that the UCDs are old (mean age 10.8 +/- 0.7 Gyr) and (generally) metal rich (mean [Fe/H] = -0.8 +/- 0.1). The a-element abundances of the objects measured from the Lick indices are super-solar. We used these measurements to test the hypothesis that UCDs are formed by the tidal disruption of present-day nucleated dwarf elliptical galaxies. The data are not consistent with this hypothesis because both the ages and abundances are significantly higher than those of observed dwarf galaxy nuclei (this does not exclude disruption of an earlier generation of dwarf galaxies). They are more consistent with the properties of globular star clusters, although at higher mean metallicity. The UCDs display a very wide range of metallicity (-1.7 < [Fe/H] < 0.0), spanning the full range of both globular clusters and dwarf galaxy nuclei. We confirm previous reports that most UCDs have high metalliticities for their luminosities, lying significantly above the canonical metallicitiyluminosity relation followed by early-type galaxies. In contrast to previous work, we find that there is no significant difference in either the mean ages or the mean metallicities of the Virgo and Fornax UCD populations.

Given the current trend towards further miniaturization in the optoelectronics assembly, the controllability of epoxy behaviour (i.e. joint fillet) on the substrate to which the epoxy-based adhesives are used to bond the optical component onto the substrate becomes important to allow the reduction of the optoelectronic modules with high packing density. In this paper, the self-assembly monolayer (SAM) with a multi-stage coating method was generated successfully on the hybrid Au/AlN substrate surface. The thermal stability and the epoxy bleed testing of two different SAMs systems, CH3(CH2)17SH + CF3(CF2)16COOH and CF3(CF2)7CH2CH2SH + CF3(CF2)16COOH was measured and compared in order to understand the temperature tolerance of such system and therefore the effectiveness of reducing the bleeding in the subsequent assembly process, e.g. the soldering process. The results suggested that CF3(CF2)7CH2CH2SH + CF3(CF2)16COOH exhibited higher thermal resistance than that of CH3(CH2)17SH + CF3(CF2)16COOH. By analysing the polar and dispersive components of the surface free energy, a quantified guideline was suggested to be used during assembly process to verify the possible bleeding issue.

A degree of surface contamination has been found to be beneficial for assembly quality of optoelectronics because it reduces the surface free energy of the ceramic substrates, therefore inhibits bleed of the epoxy adhesives used to assemble components to them. This study aimed to examine the implications for process control of current industrial practice where the control of ceramic surface free energy is not considered. This has been achieved by identifying and characterising the potential sources of the contamination found on ceramic sleds, which had passed through the optoelectronic supply chain, so that the variation in chemical composition and the degree of contamination could be determined.Two types of ceramic substrates, aluminium oxide and aluminium nitride were cleaned by plasma, then stored in commercial polymer waffle packs used for transportation and a variety of storage atmospheres for one month. XPS measurements to characterize the surface chemistry were subsequently carried out following the storage to identify the composition of contamination that had built up. Contact angle and bleed distance measurements were also made to quantify the effect of the contamination on the wetting properties of the contaminated surfaces.It was found that the composition of the contamination was not directly associated with the storage method or environment, but the quantity was. The highest degree of contamination occurred on samples stored using the industrial standard method of containment in polymer waffle packs with paper and polyethylene anti-static inserts, higher even than storage in open air. The major source of the contamination in this case was probably from the inserts, with a much smaller contribution from the waffle pack. The levels of contamination built up in such case produced apparent surface free energies only slightly lower than 30mJ/m2, the threshold for acceptable levels of bleed to occur during the assembly process. This has indicated that if storage were to be used as a method of controlling epoxy bleed, it is likely that episodes of epoxy bleed would occur in a random manner on the production line, due to variation in the sample storage conditions and tendency to adsorb contaminants.

Chemical and physical variability in the as-received state of aluminium oxide and aluminium nitride ceramic substrate materials used in optoelectronic modules currently leads to a process yield less than 100% when adhesives are used for assembly and interconnection. The phenomenon of epoxy bleed is a contributing factor to this yield and steps are not yet taken in the industry to control or inhibit the undesirable wetting.Standard surface texture measurement techniques, XPS and contact angle measurements were implemented to characterise and compare commercial as-received samples. The quality controls currently in place are assessed and additional analysis methods in the QC stage are suggested for increasing yield. Commercially available conductive and thermally conductive adhesives, also used in optoelectronic module manufacture, were studied along with the surfaces.In this work the surface property measurements, wetting observations and shear failure modes are compared and discussed. It was found that varying as-received surface properties did not affect adhesion strength between the adhesives and ceramics enough to induce an undesirable failure mode, although epoxy bleed distance varies dramatically with varying surface conditions.

Our VLT (FLAMES) observations near NGC1399 investigate the connection between ultra-compact dwarf galaxies (UCDs), NGC1399 globular clusters and intra-cluster globulars. We have uncovered 30 faint compact stellar systems in the Fornax galaxy cluster, adding to 62 bright UCDs previously reported. The magnitude limit of these stellar systems extends down to the globular cluster domain. We detect a filament of UCDs and globular clusters stretching across NGC1399 and find weak evidence for its rotation. These compact stellar systems not only congregate around several cluster galaxies but are also widely distributed through intra-cluster space.

Maintaining cleanliness of substrates for assembly in optoelectronic modules is important where surfaces will be subjected to further processes in which the surface properties can affect performance. Cleanliness is counter productive when considering epoxy bleed, since the carbon based contamination of surfaces has been seen to reduce surface free energy and inhibit the spread of epoxy material. The origin of this contamination can be from a number of sources including atmosphere, handling, surface treatments and outgassing from storage media. Whilst allowing contamination to remain on the surface can be an effective means of controlling the epoxy bleed, it is not a reliable solution through lack of controllability. Identifying and quantifying this contamination will be a useful step towards the understanding and control of epoxy bleed, whilst its removal will homogenise all surfaces allowing controllable solutions to be implemented. The substrate materials of interest were aluminium oxide and aluminium nitride, which are commonly used in the optoelectronics industry. Storage methods used in industry were recreated for the purpose of this study with storage of samples in tin foil used for comparison. Samples were stored in commercial polymer waffle packs in a variety of atmospheres which they might experience in industry, on an industrial site, for one month. XPS measurements were made following storage to identify the composition of the contamination and its source. Both the degree of carbon contamination and the functional groups of any adsorbed species are known to affect surface energy and epoxy bleed. Therefore narrow band XPS spectra for carbon were analysed for all samples. Of the many methods which could be employed to remove the surface contamination, solvent, plasma cleaning and firing were chosen for their suitability and due to their availability to industry. XPS was performed on samples following cleaning. It was found that the composition of the contamination on the surfaces was not linked to their storage method but the quantity of contamination was. Storing ceramics in polymer waffle packs does not protect them from build up of carbon contamination regardless of storage atmosphere. The use of tin foil for storage can reduce the degree of contamination presence significantly, but not prevent build up entirely. A high degree of bleed was seen in both samples cleaned but not stored as well as in samples cleaned after storage, showing the effects of storage contamination are easily reversed. While storing ceramics for an extended period of time will allow build up of sufficient contamination to stop bleed occurring, samples fresh from suppliers will not have built up sufficient contamination to reduce the surface free energy to a degree such that bleed will not occur.

Ultra-compact dwarf galaxies (UCDs) are a new type of galaxy we have discovered in the central region of the Fornax and Virgo clusters. Unresolved in around-based imaging, UCDs have spectra typical of old stellar systems. Ninety-two have been found in Fornax [1, 3], making them the most numerous galaxy type in the cluster. Although they form a cluster wide population, an over-density surrounds the central cluster galaxy, NGC1399, fueling controversy over their nature and origin. Several formation scenarios have been proposed. UCDs may be the remnant nuclei of tidally stripped dE,N galaxies [2] or they may be the bright tail of the globular cluster (CC) population associated with NGC1399 [3,"UCos"]. Alternatively they may be the first spectroscopically confirmed intracluster globular clusters (IGCs) in Fornax, resulting from hierarchical star cluster formation [4] and merging in intracluster space. The 5 brightest Fornax UCDs have M/L ratios indicating at least some dark matter, unlike typical GCs.

For high signal-to-noise ratio GMOS-N and AAOmega spectra, we have measured line-strength indices in the Lick/IDS system for several luminous and spatially dispersed compact stellar systems (CSSs) located in the Virgo and Fornax galaxy clusters. We estimate their [alpha/Fe] ratios, ages and metallicities using a simple (single-burst) stellar population model We confirm that the Virgo core region luminous CSSs (M(bj) <= -10.5) contain ancient stellar populations with subsolar total metallicities, suggesting that they comprise the bright tail of M87's GC distribution. The two Virgo intracluster globular clusters have ages and metallicities consistent with the cluster core CSSs. Two Fornax luminous CSSs also have ancient stellar populations but are at the upper end of the Virgo CSS metallicity range, while the third (UCD3) appears to be relatively young, metal-rich and with a core + halo radial profile. Our results suggest that Fornax may contain an extra population of luminous CSSs formed more recently than the ancient GC-like systems found in both clusters.

The discovery of ultra compact dwarf (UCD) galaxies has been very well reviewed by Michael Hilker in these proceedings. Here we wish to focus on the large-scale distribution of UCDs. Our study was originally motivated by a search for "M32-type" compact elliptical galaxies in the Fornax Cluster. We didn't find any of these, but we did demonstrate that morphological membership classification can overlook many compact dwarf cluster members [3]. This motivated the 2dF Fornax Cluster Spectroscopic Survey (FCSS, [4]), which measured redshifts of all objects, both "stars" and "galaxies" in the cluster centre, resulting in the detection of 5 UCDs ([5] and also [9]). High resolution imaging and spectroscopy have since established that the most luminous UCDs are a new type of object [6]. We have extended our UCD searches to fainter limits [71, finding a total of 62 compact objects filling a large region of intra-cluster space (see Fig. 1). We discuss the distribution of these objects below, noting that our working UCD definition (Fornax Cluster members barely resolved in photographic survey data with m(Bj) < 21.5 mag) may also include genuine globular clusters (GCS).

Polycrystalline aluminium oxide and aluminium nitride sleds were machined using a CO2 laser to explore the capability of the method to produce passive alignment and assembly features for use in optoelectronic assemblies. The geometry of machined features and surface texture of machined surfaces were characterised and found to be limited by the ablation method. Consequently, a KrF excimer laser was utilised in the trials for bulk machining of the ceramics but was observed also to be restricted by its slow ablation rate. However, the combined CO2 with KrF excimer laser were then employed to exploit the benefits offered by both, fast processing time of the CO2 laser and enhanced geometry and texture control with the KrF excimer laser. In this study, the geometry and surface texture generated by the individual and the combined methods are characterised and compared to identify the processing limitations. The ability for the machining methods to produce patterns of sufficient accuracy to act as passive alignment features is therefore discussed. The suitability to produce the various artifacts to enable adhesive flow control was also examined, which can be applied for micro-scale precise assembly of high density packaging. By considering the production of such features with desirable geometry and textures, the effects of the processing parameters on the bulk material and the substrate surfaces where the energy of laser beam directly interacted was particularly investigated. This will ultimately assist to establish optimum settings of processing parameters in association with the type, properties and thickness of the substrates.