Silicon and InGaAs Quadrant Photodiodes

“Quads” or quadrant photodiodes (QPDs) are segmented photodiode position sensing detectors (PSD, AKA position sensing diodes) with four planar diffused photodiode elements, which are monolithic or on the same silicon or InGaAs chip. Marktech Optoelectronics quad photodiodes have low dark current, high resolution or precision, high accuracy, high response with low noise (high S/N ratio), wide spectral ranges, good frequency bandwidth, excellent dynamic range, minimal element spacing, low operating voltages, high shunt resistance, and large active areas.

Two segment, dual element, or bi-cell photodiodes are another type of position sensing device commonly incorporated into alignment or positioning systems. While quadrant photodiodes can sense position along two dimensions or both the X & Y axes, bi-element photodiodes align or position along one dimension or axis.

Marktech’s four-element photodiode arrays or quad detectors provide flawless performance in laser alignment and nanopositioning applications. Quadrant photodiodes (QPDs) or quadrant position sensitive detectors typically have resolutions as low as 10nm using beams with optical powers from 10 to 100microWatts (MÄKYNEN). Quads can be used in auto-collimators for laser alignment, optical trackers, scanning probe microscopes, stage positioners, surface profilometers, mask aligners, beam centering systems, space sun sensors, ellipsometers, optical tweezers, tilt sensors, high accuracy displacement sensors, and other ultra-precision positioning applications. The fast response and wide operational bandwidth of QPDs have made these positioning devices dominant in the atomic force microscope (AFM) industry (Chien, et al.). Satellite communication systems can benefit from quadrant photodiodes as well. For example, quadrant photodiodes are key components in quadrant photoreceivers (QPRs) front-end devices for inter-satellite laser interferometry.

Silicon and InGaAs Photodiode Arrays

Both bi-cell and quadrant photodiodes are photodiode arrays (PDAs), with two (1X2) and four (2X2) elements, respectively. Bi and quad PDs are suitable for alignment or position sensing over a small beam displacement or position range. For laser or light beam position sensing over a larger range, longer, multi-element photodiode arrays are necessary. Marktech Optoelectronics also manufactures multi-element linear (one dimensional, 1D) and area (two dimensional, 2D) photodiode arrays with many segments for dispersive spectroscopy, refractometry, distance or range finding (triangulation position sensing), interferometry, and particle analyzers. Most photodiode arrays applications require custom-designed arrays and OEM integration, which is one of Marktech’s industry leading capabilities. Marktech’s detector experts have designed and manufactured photodiode arrays with 2, 4, 16, 20, 32, 64, and more elements.

Our InGaAs quadrant photodiodes and photodiode arrays have a wavelength sensitivity range from 600nm – 2600nm. Our silicon quadrant photodiodes and photodiode arrays have a wavelength sensitivity range from 250nm – 1100nm. These die can be packaged individually in a variety of hermetically sealed TO packages or integrated into a custom package (PLCC, COB, ATLAS hermetic SMD, ceramic carrier, etc.) to suit your specific application and pin-out design specs.