Average Optical Loss Research Articles

Fiber-connectorized multiwavelength 2×2 switch structure using a fiber loop mirror

A fiber-connectorized multiwavelength 2×2 switch structure is introduced for the first time that deploys a fiber loop mirror (FLM) arrangement with polarization control. Switch operation is achieved via a programmable waveplate effect rather than an optical power consuming long fiber loop length non-linear optical effect. The results from an experimental four-wavelength (i.e., 1546.92 nm, 1548.52 nm, 1550.12 nm, and 1551.72 nm) proof of concept switch using two mechanical fiber-based polarization controllers embedded in a short 7 m fiber loop indicates an average optical coherent crosstalk of −31.2 dB. Presently, optical loss is mainly limited by the WDM devices used in our experimental setup. Hence, without the WDM multiplexers, an average optical loss of 2.22 dB is measured over a 50 nm optical bandwidth. Also, an average 0.08 dB polarization dependent loss is measured for this broadband switch.

Versatile multi-wavelength fiber-optic switch and attenuator structures using mirror manipulations

Compact frequency-selective fiber-optic switch (FOS) and attenuator structures are proposed based on the use of 2N hinge-type flapping micromirrors in a linear array geometry and piston-type micromirrors in a two dimensional (2D) array format. The flapping micromirrors are designed to be positioned in a compact low-loss in-line geometry that provides ease in optical alignment. The results of an experimental 4-wavelength proof of concept FOS using two macro-mirrors shows an average optical interchannel crosstalk of <−33 dB and an average total loss of <10.8 dB. Both numbers are limited by other devices in our self-aligning structure, as the unique in-line mirror placement design provides a low 0.4 dB free-space coupling average optical loss. Using sub-micrometer motion of 2D piston-type micromirrors, an alternate higher speed FOS based on the Michelson interferometer structure is proposed. Experimental proof of concept data for this FOS indicates an average optical loss of 9.81 dB and a loss fluctuation of ±0.06 dB within a 50 nm bandwidth. This optical loss value is again limited by the WDM devices, fiber adapters, three-port optical circulators, and free-space coupling efficiency. An average optical interchannel crosstalk of −24.4 dB is measured, limited by the resolution of the translation stage used in the experiment. Using these FOS architectures, variable fiber-optic attenuator structures are also introduced. An average maximum optical attenuation of 24.38 dB is measured within a 50 nm bandwidth for our attenuator using the interferometric FOS design.

Digitally controlled fault-tolerant multiwavelength programmable fiber-optic attenuator using a two-dimensional digital micromirror device

A digitally controlled multiwavelength variable fiber-optic attenuator using a two-dimensional digital micromirror device (DMD) is introduced. The results from an experimental four-wavelength (i.e., 1546.92, 1548.52, 1550.12, and 1551.72 nm) proof-of-concept attenuator indicate a 26-dB dynamic range and 11-bit resolution. The measured attenuator average coherent optical cross talk per wavelength channel is -38 dB , limited by the additive noise resulting from the nonideal isolation of the optical circulator and the attenuator module. The average optical loss for our experimental attenuator is 15 dB and is limited mainly by the visible-mode DMD that is used as a 1550-nm infrared window device. Our theoretical estimate of a <8-dB loss optimized attenuator can be used for equalization in multiwavelength fiber-optic communications with as many as 108 wavelengths.

Fault-tolerant dense multiwavelength add–drop filter with a two-dimensional digital micromirror device

A two-dimensional digital micromirror device- (DMD-) based add-drop filter is introduced for dense wavelength-division multiplexed applications. Features of the filter include polarization-insensitive operation, low interchannel cross talk parallel processing, and a fault-tolerant design. Experiments include evaluation of a parallel-beam-fed interchannel cross-talk with a 25-beam mask and a three-color (red, green, blue) filter operational test that indicates output-port average switching optical signal-to-noise and multiwavelength cross-talk ratios of 24 dB. The DMD-based average optical loss for the filter is -2.85 dB for visible-light free-space operation, whereas a -8.88-dB optical loss is measured for a fiber-coupled filter operating at 1319 nm.

Ultrahigh -47-dB optical drop rejection multiwavelength add–drop filter using spatial filtering and dual bulk acousto-optic tunable filters

A new high-speed, ultrahigh cross-talk-suppression multiwavelength add-drop optical filter structure is demonstrated with two bulk acousto-optic tunable filters. With simple spatial blocks, an average -47-dB optical suppression is measured for the unwanted wavelengths at the filter output ports. The filter is tested for the three standard visible wavelengths, red, green, and blue, and demonstrates a switching time of 0.65micros and an average optical loss of 5 dB. Applications for this filter include multiwavelength switching applications such as wavelength-division-multiplexed optical communications.

Injection moulded optical alignment sleeve for singlemodeconnection

Plastic optical alignment sleeves for singlemode connection were successfully fabricated by the thermoset injection moulding process. The split sleeves exhibit excellent dimensional accuracy (± 2 µm) and have extremely smooth surfaces (Ra < 0.1 µm). They are compatible with SC-type connectors and the average optical loss is < 0.1 dB for singlemode SC plugs.

Fusion splicing of heavy metal fluoride glass optical fibres

Heavy metal fluoride (HMF) glass optical fibres were spliced by fusing the two ends of fibres using a DC arc. An average optical loss of 0.08 dB per splice and strengths of up to 600 M Pa were achieved for fusion splices using an inert gas purge during splicing. Estimates are made to determine the feasibility of achieving a splice loss of 0.005dB for singlemode (HMF) fibres.

Transmission experiments in the 1.2–1.6 μm wavelength region using graded-index optical fiber cables

Abstract Optical fiber transmission systems with extremely long repeater spacing are very attractive for various applications both in land and undersea communication systems. This paper describes the results of transmission experiments, using low-loss fibers in the 1.2–1.6 μm wavelength region. Graded-index optical fibers having an optimum profile at 1.27 μm were manufactured in cables. Average bandwidth was 1,275 MHz-km, and the average optical loss was 0.6 dB/km. The 52.6-km and 62.3-km repeater spacings were realized at 100 Mb/s and 32 Mb/s transmission, respectively, using InGaAsP/InP LD and Ge-APD. The 21.5-km and 12.0-km repeater spacings at 32 Mb/s were also realized by 1.2μm and 1.5μm LEDS, respectively.