Marktech Optoelectronics Announces New InGaAs Quad and Array Photodiodes for Laser Alignment and Position Sensing Applications

September 21, 2022 – Latham, NY, USA –  Marktech Optoelectronics, Inc. (www.marktechopto.com)(Marktech), a privately-held leading designer and manufacturer of standard and custom optoelectronics, including UV, visible, near-infrared (NIR), and short-wavelength infrared (SWIR) emitters, detectors, InP epi wafers, and other compound semiconductors, today announced their offering of cutting-edge InGaAs quadrant and array photodiodes for laser alignment and position sensing applications.

 “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 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 (Ref 1). 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 (Ref 2). Satellite communication systems can benefit from quadrant photodiodes as well. For example, quadrant photodiodes are critical components in quadrant photoreceiver (QPR) front-end devices for inter-satellite laser interferometry.

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 more extensive range, longer, multi-element photodiode arrays are necessary. Marktech Optoelectronics can manufacture custom 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. Many photodiode array applications require custom-designed arrays and OEM custom integration, 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.

Advantages of InGaAs Position Sensitive Detectors
InGaAs quadrant, bi-segment, and multiple segment array position-sensitive detectors have several advantages over imaging sensors (CCD, CMOS, focal plane arrays, etc.), such as high position resolution, fast response time, lower cost, and straightforward signal conditioning circuit designs. In addition, InGaAs linear arrays are employed in pulsed laser or direct time of flight (TOF), phase shift or indirect time of flight (TOF), and triangulation position sensors.

InGaAs positioning sensitive detectors have a further advantage over silicon PSDs in their ability to sense eye-safe laser wavelengths in the NIR and SWIR bands. In addition, specific SWIR wavelengths can “see” or detect through plastics, fog, smoke, or moisture, which is an advantage over visible and NIR PSDs. For example, water is opaque when viewed at specific wavelengths such as 1400nm, so an InGaAs PSD with a 1400nm SWIR LED emitter could sense water levels in a plastic container or tank. In a factory application, InGaAs detectors with 800nm to 2600nm sensitivity should have no or fewer false triggering events from high brightness LED work lights and other stray light sources in the visible band. Detectors with ambient light immunity are beneficial in triangulation position sensing systems and LiDAR devices.

InGaAs Wavelength Sensitivity Range

Our InGaAs quadrant photodiodes and photodiode arrays have a wavelength sensitivity range from 600nm to 2600nm (600nm to 1700nm for our 1.7µm InGaAs PDs and 800nnm to 2600nm for our 2.6 µm InGaAs PDs). Our silicon quadrant photodiodes and photodiode arrays have a wavelength sensitivity range from 250nm to 1100nm. These die can be packaged individually in a variety of hermetically sealed TO packages or integrated into a custom package (PLCC, COB, hermetic SMD, ceramic carrier, etc.) to suit your specific application and pin-out design specs. Marktech has several class 100 cleanrooms for the advanced packaging and assembly of custom InGaAs and silicon photodiode devices on rigid PCBs, flexible circuits, and OEM-specific designs.

Custom silicon quadrant photodiode array

made in Marktech’s factory in Simi Valley, CA.

Custom InGaAs Photodiodes and Packaging

Marktech routinely manufactures custom photodetectors to OEM specifications from prototype to production volumes.  The range of Marktech’s custom photodetector engineering and manufacturing, including custom InGaAs photodiodes:

• Wafer-level device design
• Semiconductor wafer fabrication of InGaAs photodiode devices
• Conversion of InGaAs devices on wafers to die or chips
• Packaging of InGaAs die in:
  • Standard packages (TO can, PLCC, ceramic, etc.)
  • Proprietary packages (ATLAS hermetic SMD)
  • OEM-specific custom packages

Marktech can co-package InGaAs photodiodes with emitters, filters, and transimpedance amplifiers (TIAs). Marktech’s U.S. factory in Simi Valley, CA, has a similar level of competency in producing silicon photodiode detectors. In addition, silicon and InGaAs photodiodes are assembled in the same package for wide spectral band detection applications (MT03-041 TO-39 Metal Can Flat Lens and MT03-047 Ceramic SAW Package). 

Marktech Optoelectronics has vertically integrated capabilities to custom design and fabricate InGaAs photodetector and photodiode array devices on wafers and then dice and package these photodiode chips with any required emitters, amplifiers, filters, and components for specific applications. This vertical integration allows Marktech to precisely control the performance and quality of the photodetectors and assemblies designed and manufactured for our customers.

Consult with Us Today About Your Design Project

Using Marktech Optoelectronics advanced InGaAs photodetectors in new products under development will likely lead to breakthrough designs in many analytical instruments, medical diagnostics, and industrial sensing applications.

If you have specific technical or application questions regarding your optoelectronics design project or are just interested in learning more about Marktech’s InGaAs and silicon photodiodes, then please reach out to us through the following:

• Contact our application engineers: info@marktechopto.com
• Request for information (RFI) or request for quote (RFQ) form: Contact Us
• For major photodiode engineering projects, contact our U.S. factory directly:
  Vince Forte, Chief Technology Officer, v.forte@marktechopto.com
  Barry Jones, Business Unit Manager b.jones@marktechopto.com