Technology Of Wavelength Tuning Based On Refractive Optical Lever And Its Application In Optical Spectrum Analyzers And Diode Lasers

With the development of DWDM, optical spectrum analyzers, which are portable and can be applied to DWDM project site, are in great demand. At the same time, the demand of diode lasers is also increasing day by day. To fit all the application, the lasers must have steady frequency or be tunable. Focusing on the optical spectrum analyzer and the external-cavity diode laser, this paper describes a novel method for wavelength fine-selection. This method employs a refractive optical lever system, the structure of which is simple. It also has low cost, and is easy to be carried out. This is a significant improvement not only on the wavelength discrimination capability of OSA for demanding DWDM test applications, but also on technology of frequency stabilization of lasers. In this paper, we firstly introduces the refractive optical lever principle. We then conclude that the beam deviation angle is a weak function of the beam incident angle, and attain the curves of angular displacement sensitivity of the optical lever system for wedge prisms with wedge angles of 1, 2 and 3 degrees respectively. We also find the amplification factors for wedge prisms with different wedge angles. In addition, the optical lever system is used to improve the wavelength selecting accuracy and resolution of optical spectrum analyzer. The grating rotation angle is compared with the wedge prism rotation angle. Through experiment we find that the application of refractive optical lever principle for optical spectrum analyzer is feasible. Finally, we propose a method of using refractive optical lever for wavelength fine-selection in external-cavity diode laser. Moreover, this principle can be used for diode laser frequency stabilization.