Total Internal Reflection Mirrors Research Articles

Self-aligned high-quality total internal reflection mirrors

High-quality total internal reflection (TIR) mirrors are fabricated by a new self-aligned etch process using SiCl/sub 4/ reactive ion etching (RTE). The self-aligned etch process requires only a single SiO/sub 2/ mask layer without additional dielectric depositions and lift-off steps. The reflectivity of the TIR mirrors are measured by characterizing InGaAs-GaAs-AlGaAs strained-layer quantum-well heterostructure crank lasers that consist of crank-shaped ridge waveguides with two TIR mirrors and two cleaved facets. It is found that the self-aligned TIR mirrors have a very high reflectivity of 0.90 (0.46 dB/90/spl deg/ loss).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Lateral-mode discrimination in ridge waveguides by misaligned total internal reflection mirrors

Lateral-mode discrimination by misaligned total internal reflection (TIR) mirrors in multimode ridge waveguide structures is proposed. The effects of angular misalignment in TIR mirrors and index steps in ridge waveguides on the modal reflectivity is analyzed by a plane wave expansion method. The modal reflectivity of a high order mode decreases more rapidly than that of a fundamental mode as the angular misalignment of TIR mirrors increases. It is found that a fundamental mode can have high modal reflectivity (/spl sim/0.9) with significant lateral-mode discrimination over high-order modes if the ridge waveguides have large index steps.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

InGaAs-AlGaAs-GaAs strained-layer quantum-well heterostructure square ring lasers

The processing and optical characteristics of an InGaAs-AlGaAs-GaAs strained-layer quantum-well heterostructure square ring laser (4 /spl mu/m width and 50-/spl mu/m/side length) with two output waveguides and two narrow physical gap couplers are described. The ridges and the total internal reflection (TIR) mirrors of the square ring lasers are fabricated by two photolithographic steps with a single SiO/sub 2/ mask and planarized with polyimide such that the TIR mirrors are etched through the active region while the ridge waveguides are not. Single longitudinal mode operation is observed with a side mode suppression ratio of 20 dB. Asymmetric characteristics of emission spectra from the two output waveguides demonstrates that the square ring lasers operate in traveling wave modes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Monolithic InGaAsP-InP laser amplifier gate switch matrix

An InGaAsP-InP 2*2 laser amplifier gate switch matrix operating at 1.5 mu m with a fiber-to-fiber insertion loss of 3 dB is reported. The switch consists of passive waveguides for branching and recombining, monolithically integrated with laser amplifiers. The passive waveguides perform the signal routing, and the amplifiers provide gain/absorption in each path for on/off switching, achieving gain in the on state to compensate the losses. Dry-etched total internal reflection mirrors are employed as 90 degrees waveguide corner mirrors and also incorporated in the splitters in order to give a compact design. The on/off extinction ratio is >45 dB and the crosstalk is <-45 dB.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Fanning and photorefractive self-pumped four-wave mixing geometries

Results of recent experimental and theoretical investigations on the role of fanning in the operation of several popular photorefractive self-pumped FWM geometries, including the double phase conjugate mirror (DPCM), the ring oscillator, the semilinear mirror, the system of two coupled DPCMs, and the total internal reflection (TIR) mirror, are presented. The results can be divided into two groups. Geometries of the first group (the DPCM and the ring oscillator) have soft excitation thresholds. Geometries of the second group (the semilinear mirror, the system of the two DPCMs and the TIR mirror) have hard excitation thresholds. Geometries of the first group experience a noticeable influence of fanning only when the level of fanning of a single pumping beam passing through a crystal, is high. Geometries of the second group, such as the semilinear mirror, the system of two DPCMs, and the TIR mirror without fanning, are not self-starting.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>