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Pump and signal combiner for bi-directional pumping of all-fiber lasers and amplifiers(6)

Pump and signal combiner for bi-directional pumping of all-fiber lasers and amplifiers(6)

4.4 Experimental results

In order to verify the simulations, two fiber combiners with a single pump port based on the setup described in Section 2 were developed. For the first combiner an IF with a low TR of 2.6 and a short TL of 9.5 mm was fabricated. In the case of the second combiner the TR and the TL were increased to 6.7 and 18 mm, respectively. For both combiners the geometrical dimensions of the obtained tapered IFs were measured with an optical microscope. After completion of the fabrication, both combiners were optically characterized. Therefore, each PFF (pump port) with a NA of 0.15 was connected to a pump diode (Oclaro BMU25) with a pigtail fiber delivering a maximum output power of ~25 W at a wavelength of 976 nm. The delivery fiber of the pump diode had parameters identical to the PFF.

The experimental results for the first fiber combiner are shown in Fig. 6(a)

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Fig. 6 Coupled and transmitted power measured for a fiber combiner with one pump port with (a) a TL of 9.5 mm (TR of 2.6) and (b) a TL of 18 mm (TR 6.7), * ratio of coupled or transmitted power to total diode power in percent.

. Due to the low TR of 2.6, an experimental pump coupling efficiency of only 74% was achieved. The residual pump power was almost completely measured as TP, with a power fraction of 25.3%. The simulations for the coupled as well as the TP show good agreement with the experimental results, and confirm that in the case of a low TR of 2.6, the pump power is only divided into coupled power and TP. In Fig. 6(a) it can be seen that in the simulations the sum of the coupled and TP is 99.9%, corresponding to 0.1% of pump light rays not detected in the simulations. This can be treated as a simulation error. That the measured sum of coupled pump power and TP is only 99.3% can be explained by measurement uncertainties, marginal splice losses and additional power losses in the fiber component caused by dust particles. Since the thermal load of this fiber combiner design is negligible it would be feasible to couple several kW of pump power, but with the disadvantage of a moderate coupling efficiency of about 75% and consequently a undesirable overall efficiency for high power laser system.

For the second fiber combiner, depicted in Fig. 6(b), a higher pump coupling efficiency of 95.2% (96.0% in simulation) was measured as compared to the first combiner presented in Fig. 6(a) due to the increase in TR and TL. Following the simulations the residual pump power of 4% can be divided into TP, PCT and PAA with 2.4%, 0.6% and 0.9%, respectively. Again, the missing pump power of 0.1% was associated with an error owing to undetected power in the simulations. For the TP a fraction of 2.3% was measured and shows very good agreement with the simulation (2.4%), i.e. more than 50% of the total power loss was TP. This fraction of power represents no risk for damage to the fiber component. Due to the excellent agreement between simulation and experiment, the simulated PCT-fraction of only 0.6% is a good value for an estimate of the thermal load of the coating of the TF. Based on the simulations and experiments an error of less than 1% of the pump input power can be assumed for the PCT-fraction.

Unfortunately, the power fractions PAA and PCT are difficult to measure and therefore could not be experimentally determined. In future work an indirect measurement of PCT will be realized by measuring the coating temperature of the CWDM Module. In summary, the simulations describe the coupling efficiency as well as the fraction of TP very well, and thus, serve as a very good estimation for the fraction of PCT and PAA.

DK Photonics – www.dkphotonics.com specializes in designing and manufacturing of high quality optical passive components mainly for telecommunication, fiber sensor and fiber laser applications,such as PLC Splitter, WDM, FWDM, CWDM, DWDM, OADM,Optical Circulator, Isolator, PM Circulator, PM Isolator, Fused Coupler, Fused WDM, Collimator, Optical Switch and Polarization Maintaining Components, Pump Combiner, High power isolator, Patch Cord and all kinds of connectors.

Fiber Optics Sensors Provide Early Warning for Landslides-DK Photonics

CASERTA, Italy, Sept. 29, 2014 — Fiber optic sensors could warn people of imminent landslides, potentially saving lives and reducing destruction.

A team at the Second University of Naples is developing sensor technology that could detect and monitor both large landslides and slow slope movements. The researchers hope to mitigate the effects of these major natural disasters, similar to the way hurricane tracking can prompt coastal evacuations.

Optical fiber sensors embedded in shallow trenches within slopes would detect small shifts in the soil, the researchers said. Landslides are always preceded by various types of pre-failure strains, they said.

While the magnitude of pre-failure strains depends on the rock or soil involved — ranging from fractured rock debris and pyroclastic flows to fine-grained soils — they are measurable. Electrical sensors have long been used for monitoring landslides, but that type of sensor can be easily damaged, the researchers said. Optical fiber is more robust, economical and sensitive.

“Distributed optical fiber sensors can act as a ‘nervous system’ of slopes by measuring the tensile strain of the soil they’re embedded within,” said professor Dr. Luigi Zeni.

The researchers are also combining several types of optical fiber sensors into a plastic tube that twists and moves under the forces of the pre-failure strains. This will allow them to monitor the movement and bending of the optical fiber remotely to determine if a landslide is imminent.

The use of fiber optic sensors “allows us to overcome some limitations of traditional inclinometers, because fiber-based ones have no moving parts and can withstand larger soil deformations,” Zeni said.

He added that such sensors can be used to cover several square kilometers and monitored continuously to pinpoint critical zones.

The team will present their research at Frontiers in Optics in Tucson, Ariz., next month.

Fiber Optic Connector Market Forecast-DK Photonics

According to ElectroniCast, multifiber / multichannel fiber optic connectors are set for explosive growth, led by MXC™ fiber connectors with triple-digit increases through 2018…

Aptos, CA (USA) – September 22, 2014 —ElectroniCast Consultants, a leading market & technology forecast consultancy addressing the fiber optics communications industry, today announced the release of their annual market forecast and analysis of the use offiber optic connectors and mechanical splices in communication applications.

According to ElectroniCast, the worldwide fiber optic connector/mechanical splice consumption value reached $2.63 billion in 2013. Multimode fiber optic connectors led the consumption value in 2013 with a 64 percent market share. The use of multimode fiber optic connectors is forecast to increase at a rate of 14 percent per year, from $1.68 billion in 2013 to $3.24 billion in 2018.

“The multimode LC small form factor connector is forecast to maintain the leadership position in relative market share throughout the forecast period, as well as increasing at an average annual rate of 20 percent,” said Stephen Montgomery, Director of the Fiber Optic Component group at ElectroniCast.

The fastest annual growth is set to come from the use of multifiber/multichannel fiber optic connectors are set for explosive growth, led by MXC™ fiber connectors with triple-digit increases through 2018. The newly-release connector design enables more fibers (up to 64 fibers at 25G) to be accommodated in fast-paced server/storage data center and other applications. Both the single-mode and the multimode MXC fiber optic connectors are forecast to reach strong values by 2018.

Other new fiber optic connector designs, besides the MXC connector, are planned for deployment to address the high-density/high-speed data speeds of 25Gbps or greater in the next couple of years.

“Field-installable connectors for indoor and outdoor use are increasing in demand and thus are making a big-splash in the overall connector product lines of several competitors. Fiber optic connector-types, such as SC, ST, LC, FC and even the MPO and other possibilities are finding their way to the marketplace. Both mechanical-splice and fusion-splice technologies are meeting the requirements in the field-installable fiber optic product availability,” Montgomery added.

The global fiber optic connector/mechanical splice consumption is driven by a dramatic increase in bandwidth demand beyond the limits of copper. As optical fiber use migrates closer and closer to the end user, where cable lengths are shorter with higher fiber counts, the requirements for jointing fibers becomes more critical. Splicing and connecting, play a significant role in a network’s cost and performance.

There are over 140 vendors competing for the global fiber optic connector/ mechanical splice market, which ElectroniCast tracks in a product matrix showing participation in the following: connectors, cable assemblies, optical backplanes, and fiber optic installation apparatus; however, is dominated by a few companies that have a broad base in various interconnect products.

DK Photonics – www.dkphotonics.com specializes in designing and manufacturing of high quality optical passive components mainly for telecommunication, fiber sensor and fiber laser applications,such as WDM, FWDM, CWDM, DWDM, OADM,Optical Circulator, Isolator, PM Circulator, PM Isolator, Fused Coupler, Fused WDM, Collimator, Optical Switch and Polarization Maintaining Components, Pump Combiner, High power isolator, Patch Cord and all kinds of connectors.

Ovum: Optical components market to grow 8% in 2014 from $6.8 bn in 2013

The global optical components (OC) market is expected to grow 8 percent in 2014 from $6.8 billion in 2013, said Ovum.

In 2013, the OC market increased 3 percent from 2012. Ovum said main growth drivers in 2013 were data communication sales driven by large data centers, 100G coherent demand, and unexpected growth in sales of transceivers for fiber-to-the-antenna applications for 4G build-outs.

“Demand for 100G metro–optimized transmission gear will begin shipments and ramp in 2015. Multiple component vendors introduced components and pluggable optics for 100GHz DWDM in anticipation. Opportunities are also emerging in the data center for high-speed interconnects,” said Daryl Inniss, practice leader for Telecoms Components at Ovum.

In the first quarter of 2014, the optical components market declined 1 percent sequentially and grew 7 percent compared to the year-ago period. New lower telecom prices were one of the main reasons for the marginal growth in OC on quarter-on-quarter basis.

Ovm said demand for 100G components for coherent transmission in WAN, datacom transceivers at 10 and 40G, and fiber-to-the-antenna transceivers is expected to continue. Traffic continues to increase, and high-speed optics being used in new applications are helping to drive the market forward.

The WAN OC segment, which includes components in telecom carriers’ core and metro networks, the largest segment, will grow at a compound annual growth rate (CAGR) of 11 percent to $7 billion in 2019. Demand for 100G components and modules is a big driver for growth in WAN. Ovum expects strong demand for pluggable coherent transceivers in 2015.

Datacom will be expanding at a 16 percent CAGR to reach $4.2 billion in 2019 — led by demand for 10 and 40G components in the early years and then 100G in the later years driven by the availability of server ports supporting data rates greater than 10G.

Access — including CATV, FTTx and transceivers for the fiber-to-the-antenna application — will decline at 2 percent CAGR to $1.1 billion in 2019. The decline will be driven by the FTTx application, where volumes are nearly constant through the forecast period but price declines are projected to pull down revenues.