Optical isolator

Fig. 6.20. The schematic diagram of experimental set-up to study photoemission of 02- / - quartz vial 2 - quartz window 3 thermostating jacket 4 - aluminum shield 5 - filter 6 - thermostating jacket 7 - blue glass 8 - sensor 9 - platinum rings 10 - glass covered weight 11 - 13 - lenses A, B - jackets providing optical isolation of chambers.

Installation in which these studies were conducted is shown in Fig. 6.20. It was composed of two optically isolated chambers. The chamber to generate singlet oxygen contained a sensibilizer (tripaflavin. 

The polymer can also be used to tailor the selectivity and sensitivity of the optical sensor due to enrichment of the analyte by the polymer material. Furthermore, the polymer may the permeable for gases but not by ions again inducing selectivity for certain analytes. Finally, the polymer can provide optical isolation against ambient light and thus prevent bleaching and light interference. 

Figure 24.8 Experimental schematic of the multiplexed diode-laser sensor system used to measure CO, CO2, CH4, and H2O absorption by sampling hot combustion gases 1 ECDL 1.49-1.58 pm 2 optical isolator 3 — fiber coupler 4 — 1x2 fiber splitter 5 — etalon 6 — InGaAs detector 7 — DEB 1.65 pm 8 — 2 x 1 fiber combiner 9 optical fiber 10 fiber pitch 11 — concave mirror 12 — multipass...

Applications making use of the nonlinear absorption of dyes are passive Q-switching in solid-state lasers, pulse shaping, pulse intensity measurements of high-power ultrashort pulses, optical isolation between amplifier stages of high power solid-state lasers, and pulse width measurements of ultrashort pulses by the two-photon-fluorescence (TPF) method. 

The imager proposed in US-A-S030828 has parallel elongate cavities formed within a substrate, photosensitive detector elements formed within the cavities and an optical insulating layer adjacent each of the cavities to optically isolate the cavities from each other. The elongate cavities provide an increased detector element surface area which increases the sensitivity. The optical isolation reduces cross-talk among adjacent detector elements. 

Parallel elongate cavities 13 and a layer of optical isolating material 18, surrounding each of the cavities, are formed within a substrate 10 of CdTe. The cavities each have a vertical wall 15 and a pyramidal floor 16. The wall and floor of each cavity has a body of detector material, HgCdTe, formed as a layer thereon. The body of detector material is comprised of a layer of a first type 22 and a layer of a second type 24. Individual electrical contacts 28 and a common electrical contact 29 are provided. An insulating layer 32 insulates the common contact from the substrate. A diffusion layer 34 of semiconductor material of the second type provides electrical communication between the common contact and the material of the second type formed in the cavity. The cavities may have cylindrical walls and a round floor. 

An important application for garnets is for isolators in optical communications systems. Reflections from end-faces of components and interconnections in an optical transmission line have a destabilizing effect on the operation of the laser sources and have to be eliminated. This is achieved using an optical isolator , the optical analogue (2 typically in the range 1.30—1.55 /mi) of the microwave isolator described in Section 9.5.5. 

ECDL External Cavity Diode Laser OI Optical Isolator L Lens AOS Acousto-Optic Switch PZT Piezo-Electric actuator Me Cavity mirror APD Avalanche Photodiode PC Pressure Controller P Pump... 

Fiber-optic chemical sensor with an indicator chemistry at the distal end. The overcoat provides some mechanical stability and, when dyed black, can also serve as an optical isolation to prevent ambient light from entering the flber. 

Indicator-mediated optrodes frequently have an optical isolation at the fiber tip to prevent ambient light and sample from interfering in the optical system, and a fairly constant tip chemistry with its almost invariable refractive index (see Figure 18-11). However, as with plain fiber sensors, additional discriminations such as pulsed excitation plus electronic background subtraction or sequential excitation are useful techniques for improving selectivity. 

The pH-sensitive chemistry consists of a cellulosic material to which hydroxypyrene trisulfonate (HPTS) is covalently bonded. The C02-sensitive material is a fine emulsion of a hydrogen-carbonate buffer (plus HPTS) in a two-component silicone. The oxygen-sensitive chemistry is simply a solution of chemically modified decacyclene (which is strongly quenched by oxygen) in a one-component silicone. To make it insensitive toward halothane (an inhalation narcotic), it is covered with a thin layer of black PTFE, which also serves as an optical isolation. The fluorescence intensities of the three sensing spots can be related to PO2, pH, and PCO2 via modified Stem-Volmer or Henderson-Hasselbalch algorithms. 

Plastics doped by atomic clusters of ferromagnetic metals show magnetooptical properties (i.e., when subject to a strong magnetic field, they can rotate the vibration plane of a plane-polarized light), and therefore they can be used as Faraday rotators. These devices have a number of important optical applications (e.g., magnetooptic modulators, optical isolators, optical shutters, etc.). 

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