Single Total Internal Reflection Research Articles

Brewster mirror ultrafast optical parametric oscillator with high precision wavelength tuning.

We demonstrate a synchronously-pumped optical parametric oscillator (OPO) with a cavity formed from high refractive index inverted prisms, also known as Brewster mirrors. Exploiting a single total internal reflection, this is the simplest device capable of deviating a laser beam by 180∘. The OPO produced a chirped signal output tunable from 1060-1570nm with a maximum power of 114 mW. We investigate the geometric properties of ideal and imperfect Brewster mirror prisms and find the latter can provide ∼1000 × finer control of the signal wavelength when compared to cavity length tuning.

Single-prism polarizer for laser emission with higher power

Subject of study. The properties of a new prismatic polarizer-analyzer of laser (optical) emission with higher power were investigated. The polarizer was designed based on a birefringent crystal in the form of a single total internal reflection prism with a triangular cross-section. Spectral dependences of the geometry of the cross-section in the refraction plane were investigated for two selected polarizer materials. Aim. The study was aimed at designing a polarizer in the form of an individual single-element device capable of functioning in the laser beams with higher power that maintains the original direction of radiation propagation with minimum optical losses and without anamorphosis of the beam cross-section. Method. The transmission of radiation through an optically anisotropic crystalline prism with an arbitrary triangular cross-section was investigated using mathematical modeling. Snell’s equations, which were developed for refraction and total internal reflection of radiation on the faces of an anisotropic prism, were used. Based on the obtained solutions, the spectral dependences of angular structural parameters of prismatic polarizers were calculated under conditions of maintaining the collinearity of the input and output rays and their refractions on the input and output faces fixed at Brewster’s angles. The energy losses and spectral ranges of operation of prismatic polarizers composed of two selected crystalline materials with a priori defined geometry were analyzed. Main results. A new prismatic polarizer was designed and investigated. Its main feature corresponds to anisotropic total internal reflection of optical radiation from one of the faces of a birefringent single prism under Brewster’s refractions on the input and output faces. We established that the device exhibits minimum optical losses, collinearity (or coaxiality) of unpolarized and polarized beams, and no anamorphotic distortion of the cross-section of the output p-polarized beam. Furthermore, we demonstrated that in the case of virtually symmetric prisms for which the difference between the structural angles and Brewster’s angles is 3°–7°, the effect of anamorphism of the beam cross-section is negligibly small. The spectral ranges of the device operation were determined for several specific designs. A weak dependence of spectral bands on the selected orientations of the polarizer crystal was observed. It manifests in the symmetry of the obtained dependences. We demonstrated that the prisms composed of YVO4 crystals are the most advantageous for obtaining the widest spectral bands in the near- and mid-infrared spectral ranges. Angular tolerances for the divergence of the incident beams were determined based on analysis of the angular deviations of the incidence angles from the Brewster’s angles. The device can also be used in observational optics as an anisotropic equivalent of the isotropic Dove prism. The difference between the proposed device and the Dove prism is the fact that the proposed device provides the potential of observing an image in ideally linearly polarized light. Practical significance. The proposed single-element design of a prismatic polarizer with Brewster’s input and output faces enables the use of the device for polarization (or polarization analysis) of laser beams with power higher than the values for which the standard multicomponent polarizers are applicable.

Three-zone multifocus hybrid Fresnel lens concentrator.

In this paper, we designed a three-zone multifocus hybrid Fresnel lens concentrator without a homogenizer. This concentrator uses three types of prisms: a refractive prism, a single total internal reflection (STIR) prism, and a double TIR (DTIR) prism. In order to achieve a uniform irradiance distribution, the Fresnel lens is cut into four quadrants and reconnected. Moreover, by decreasing the angle of the edge ray, the hot spot effects caused by the STIR and DTIR prisms can be reduced. Finally, the three-zone multifocus hybrid Fresnel lens concentrator can achieve a geometric concentration ratio of 2121X, f-number of 0.441, optical efficiency of 76.570%, acceptance angle of ±0.268∘, uniformity of 57.002%, and hot spot criteria of 1.369.

Nine-sector three-stage Fresnel lens concentrator.

In this paper, we design a three-stage Fresnel lens concentrator with a low f number. The proposed concentrator consists of a primary optical element (POE) and a second optical element (SOE). The nine-sector three-stage Fresnel lens is composed of three types of triangular prisms: the refractive triangular prism, single total internal reflection triangular prism, and double total internal reflection triangular prism. In order to increase the uniformity and acceptance angle of the POE coupled to the SOE, the SOE is also divided into nine sectors. Finally, it is found that this nine-sector three-stage Fresnel lens concentrator can achieve a concentration ratio of 1000×; the uniformity is 25.8, optical efficiency is 81.8%, f number is 0.46, and acceptance angle is ±0.73°.

Electro-optical field sensor using single total internal reflection in electro-optical crystals

A novel electro-optical radio frequency field sensor with simple structure and high sensitivity is realized using single total internal reflection in electro-optical crystals. Without employing any waveguide structures, the minimum detectable electric field strength of the total internal reflection electro-optical-sensor is estimated to 86.52 dB μV/m (21.18 mV/m) at a resolution band width of 100 Hz for a short interaction length.

Rectangular Ring Lasers Based on Total Reflection Mirrors and Three Waveguide Couplers

Novel rectangular ring lasers containing active and passive sections are fabricated and characterized. The rectangular laser cavity is formed using four low-loss total internal reflection (TIR) mirrors and an output coupler made out of passive three coupled waveguides. The fabrication process is exactly the same as for other active and passive devices except for one deep etch step for TIR mirror fabrication. Two different lasers having active section lengths of 250 and 350 mum and total cavity lengths of 580 and 780 mum are fabricated. For both devices, lasing thresholds of 38mA are obtained at room temperature and under continuous-wave operation. Lasing is predominantly single-mode with a sidemode suppression ratio better than 20 dB. The power loss of a single TIR mirror is also determined to be about 0.5 dB. Such low-loss TIR mirrors enabled lasers with very small footprints

High-power TEM00 grazing-incidence Nd:YVO4 oscillators in single and multiple bounce configurations

We describe single and multiple grazing incidence bounce laser configurations and present results of scaling a diode-pumped Nd:YVO4 amplifier to higher powers than previously demonstrated using these schemes. In a Nd:YVO4 slab amplifier laser employing a single total internal reflection bounce configuration 50.3 W of multimode and 46.2 W of TEM00 output power is demonstrated. This is the highest power demonstration to our knowledge of the grazing incidence Nd:YVO4 laser geometry. We further describe the design of novel multiple bounce geometries, in which the laser mode can take more than one total internal reflection path through the amplifier, and show it can offer advantages especially in terms of spatial quality. A demonstration of a double bounce laser oscillator configuration shows high power 41 W of TEM00 output power with high conversion efficiency but superior spatial beam quality compared to the TEM00 single bounce laser oscillator.

Experimental observation of the Imbert-Fedorov transverse displacement after a single total reflection.

We describe a simple experimental setup with which to observe the transverse shift--also known as the Imbert-Fedorov effect-that circularly or elliptically polarized optical beams undergo after a single total internal reflection on a dielectric plane. A comparison between a theoretical model based on the conservation of energy and experimental measurements shows good agreement simultaneously for longitudinal (Goos-Hänchen) and transverse (Imbert-Fedorov) displacements.

Modeling and experimental verification of the performance of TIRF-sensing systems for oligonucleotide microarrays based on bulk and integrated optical planar waveguides

The detection of hybridization events on oligonucleotide microarrays in real time can be performed, using the optical principle of total internal reflection fluorescence (TIRF). We have investigated and compared three TIRF-sensing configurations using two bulk and one integrated optical planar waveguide as transducer platforms for oligonucleotide microarrays, which have been brought in contact with flow cells. Based on the ray optics model, expressions were derived for the calculation of the intensity of the CCD-camera signal generated by solved fluorophores in the flow cell volume. A noise analysis was performed and expressions for the calculation of the detection limit of the surface fluorophore density were derived. With a bulk optical single total internal reflection configuration a detection limit of 3.74 molecules/μm 2, with a bulk optical multiple total internal reflection configuration a detection limit of 1.83 molecules/μm 2 and with the integrated optical waveguide (IOW) configuration a detection limit of 0.013 molecules/μm 2 was numerically estimated based on background data of the bulk volume signal. The derived analytical expressions address the full system, including light source, optical waveguide and the detection unit and can serve as a tool for TIRF-system design.

Optical determination of alkali metal vapor number density in the vicinity (∼10^-5 cm ) of cell surfaces

We describe a method for determining the number density of the alkali metal vapor by use of an evanescent wave in a single total internal reflection. The method is simple to use, and it has the following useful features: It is most suitable for determining the number density of dense (>1013 cm-3) alkali metal vapor and it permits the measurement of the alkali metal vapor number density in the vicinity (∼10-5 cm) of cell surfaces. Using this method, we measured the number density of Rb metal vapor in the vicinity (∼10-5 cm) of the cell wall in cells that contain only Rb metal and no buffer gas; we found that there is no systematic difference between the Rb number density near the surface and that in the bulk.