Angle tuning

Mastuura S, Blake G A, Wyss R, Pearson J, Kadow C, Jackson A and Gossard A C 1999 A travelling-wave photomixer based on angle-tuned phase matching Appl. Rhys. Lett. 74 2872-4... 

Figure 8.19. Low Raman shift bands of naphthalene, obtained by angle tuning a HSNF filter. (Adapted from Reference 11, with permission.)...

A narrow bandpass filter chosen to match a Raman band can serve as a very simple Raman spectrometer, provided only a limited range of Raman shifts is of interest. For example, a 900 nm bandpass interference filter transmits a band centered at 1627 cm relative to a 785 nm laser. The center of the passband may be angle tuned over a limited range, and it is possible to construct a spectrum from several measurements of intensity vs. angle (6). However, the... 

LiNb03 by different pump wavelengths. Angle tuning has the advantage of faster tuning rates than in the case of temperature tuning. 

For dielectric rejection filters, the low Raman shift cutoff lies somewhere between 200 and 600 cm making observation of many inorganic materials difficult. Lewis et al. [79] were able to extend the low-wave-number range of these filter by demonstrating that by angle tuning the filters, the lower-wave-number cutoff can be shifted to a lower wave number, albeit at the expense of laser attenuation ability. 

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