Blazed grating

Figure 3.6 Use of a blazed grating at the blaze angle 4> N is the normal to the grating surface...

Fig. 93 Profilometer scans of blazed grating structures ablated into polyimide. The profile shape depends on the corrections for the polymer response, i.e., etch rate per pulse at a given fluence. REPRINTED WITH PERMISSION OF [Ref. 322], COPYRIGHT (2001) Elsevier Science...

An alternative microfabrication technique is based on replication moulding. An elastomer is patterned by curing on a micromechanical mold. This technique is termed soft lithography , and is used to make blazed grating optics, stamps for chemical patterning and microfluidics devices. Soft fithography is essentially a subtractive method. 

Fig. 7.18. Scanning electron microscopy pictnres of actual surface gratings (right) and a schematic illustration of the switching between the homeotropic state C and the low-tilt (planar) state D (left). For a symmetric grating (top) the (bulk) director of the planar state is parallel to the cell plane while for a blazed grating (bottom) it is pretilted. Modified from Jones, reproduced with kind permission of the Society for Information Display.

Losses can be improved using multiple-phase or blazed gratings in this case the efficiency can reach 80- 90% and the losses decrease to 1.5 dB (Ahderom, Raisi et al., 2002). 

By driving the Opto-VLSI with blazed gratings of different pitches, as shown in Fig. 3, optical beam steering can be achieved. The diffraction (or steering) angle for an Opto-VLSI processor, am, is given by (Xiao et ah, 2008) ... 

Fig. 2. Principle of beam steering through variable-pitch blazed grating generation.

FIGURE 11 Optical interconnects (a) beam divider (3 dB if x=50), (b) beam deflector, (c) blazed grating, (d) array generator, (e) waveguide interconnect, and (f) substrate interconnect. 

FIGURE 13 Applications of subwavelength gratings (a) antireflection surface, (b) retardation plate, (c) polarizing beam splitter, (d) diffractive lens, (e) blazed grating, and (f) wavelength-selective reflector (filter). 

Figure 10.18 Illustration of a ruled diffraction grating. Top grating orders, with m = 0 indicating the non-dispersive specular reflection. Bottom principle of obtaining increased (blazed) grating efficiency...

Figure 12.1 LC blazed-grating beam deflector by using a glass substrate with a sawtooth surface structure. PI polyimide ITO indium-tin-oxide PMMA poly(methyl-methacrylate).

Figure 12.3 Diffraction efficiency of a blazed grating as a function of the number of phase steps.

X. Wang, D. Wilson, R. Muller, et al.. Liquid-crystal blazed-grating beam deflector, Appl. Opt. 39, 6545 (2000). 

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