Abstract

Monolithic total internal reflection resonators (MoToRRs) are optical resonators in which the Gaussian modes are confined solely by total internal reflection rather titan dielectric coated mirrors. As a consequence, MoToRRs are broadband, can be operated over a wide temperature range and exhibit high finesse with appropriate material choice and surface polish. Input/output coupling is controlled via frustrated total internal reflection (FTIR) between a coupling prism and the resonator Fig.1). The frustration gives rise to a mirror reflectivity r(x) dependent on the gap x and the polarization of the resonator modes. Monolithic total internal reflection resonators (MoToRRs) are optical resonators in which the Gaussian modes are confined solely by total internal reflection rather titan dielectric coated mirrors. As a consequence, MoToRRs are broadband, can be operated over a wide temperature range and exhibit high finesse with appropriate material choice and surface polish. Input/output coupling is controlled via frustrated total internal reflection (FTIR) between a coupling prism and the resonator Fig.1). The frustration gives rise to a mirror reflectivity r(x) dependent on the gap x and the polarization of the resonator modes. Finesse 'Tf-i') and coupling c(x) of the TEMco polarization eigen- modes were measured for a 15-GHz free spectral range fused silica resonator at 1.06 pm for gaps 0 < x < 6 pm. Good agreement with the theoretical power transfer function l£_r(x)/E„|² was found. The minimum measured linewidth was 2.8 MHz (Fig.2). Uses of linear MoToRRs include optical spectrum analyzers and reference cavities and sub-micro n displacement sensors, MoToRRs fabricated from nonlinear optical materials are useful for resonant nonlinear processes such as second-harmonic generation and optical parametric oscillation, when high efficiency low-threshold, broadband or doubly resonant operation is desired. An important feature of MoToRRs is the possibility of perfect impedance matching to the resonator due to the variable FTIR coupling, simply by varying the coupling gap x. The performance of MgChLiNbOj-MoToRRs for nonlinear and quantum optics applications is evaluated. CWC37 Fig. 1. Schematic of a square ring MoToRR of index of refraction tu > 1.41, Coupling by photon tunneling occurs if a coupling prism of index ti ₃> n, sin 0, is brought within a distance x of the order of the wavelength Xo from the resonator. <- 1.6 MHz CWG37 Fig. 2. Derivative lineshape of a high-order Gaussian mode of a fused silica MoToRR, obtained by frequency modulation. The wavelength Xo — 1.06 pm. The peak-to-peak width corresponds to a FWHM of 2.8 MHz.

© 1992 Optical Society of America