Balanced Photodetector Modules
Dual-path balanced photodetectors subtract common-mode noise from two matched photodiodes — essential for coherent and interferometric measurements in DVS/DAS fiber sensing, OCT, wind measurement radar, heterodyne detection and optical delay metrology. Fiber-coupled, free-space and integrated coherent-detection options from YB Photonics.
- High CMRR Matched photodiode pairs
- 10 MHz – 1 GHz From sensing to GHz OCT
- Fiber & free-space FC/APC, flange or spatial input
- DVS/DAS ready Coherent detection tuned models
Balanced Photodetector Products by Application
Fiber-Coupled BPD for DVS/DAS & Coherent Sensing
FC/APC or FC flange balanced photodetectors optimized for distributed fiber optic sensing demodulation — differential backscatter detection, heterodyne phase recovery and coherent wind radar receive paths at 1550 nm.
APD-Based Balanced Photodetectors
Balanced detectors built from matched avalanche photodiode pairs — adjustable multiplication factor and ultra-high CMRR for weak-signal coherent detection where PIN balanced modules lack sufficient sensitivity.
Free-Space Balanced Photodetectors
Spatial-light balanced photodetectors for benchtop interferometers, free-space OCT paths and coherent optics where fiber coupling is not used — TO-packaged matched photodiode pairs with integrated differential amplification.
Integrated Coherent Detection Modules
Turnkey 1550 nm coherent detection assemblies combining balanced photodetection with optics and electronics for simplified DVS/DAS or wind-radar integration — high SNR and reliable field deployment.
How to Choose a Balanced Photodetector
- DVS/DAS coherent backscatter demodulation? Start with DAS-BPD — tuned for distributed fiber sensing coherent detection; pair with DAS modules and DAQ cards.
- OCT, wind radar or general fiber coherent detection (10 MHz–400 MHz)? BPD465 — fiber-coupled balanced module widely used in OCT, fiber sensing and wind measurement.
- 1 GHz heterodyne, OCT or optical delay measurement at 1550 nm? BPD480 — InGaAs balanced detector with FC flange, >25 dB CMRR and 1 GHz bandwidth.
- Weak-signal coherent detection needing avalanche gain? BPD570 — matched APD pair with adjustable M-factor and ~30 dB CMRR; see also APD modules for single-ended receivers.
- Free-space interferometer or spatial coherent optics? BPD230 — TO photodiode pair with spatial light input and high CMRR.
- Need a complete 1550 nm coherent receive assembly? CD-DVS/DAS-X integrated coherent detection module for DVS/DAS or wind radar systems.
- Single-ended power monitoring instead of differential? Use PIN amplified photodetectors or APD modules — balanced detectors are for subtracting common-mode noise between two optical paths.
What Are Balanced Photodetector Modules?
A balanced photodetector (BPD) uses two photodiodes connected in opposition (subtraction) so that laser intensity noise, ambient drift and other common-mode signals cancel, while differential phase or amplitude information on the two arms remains. A low-noise transimpedance amplifier outputs the difference signal on 50 Ω for lock-in amplifiers, DAQ hardware or digitizers.
In DVS/DAS and coherent fiber sensing, balanced detection is the standard receive architecture for interferometric backscatter demodulation. In OCT and heterodyne metrology, BPDs recover weak beat signals above noise floor. YB Photonics offers fiber-coupled models (DAS-BPD, BPD465, BPD480), APD-balanced units for weak light (BPD570), free-space BPD230, and integrated coherent modules — complementing our PIN photodetectors, DAS systems and narrow-linewidth lasers.
Key Specifications to Compare
| Parameter | Why it matters | Typical range in this category |
|---|---|---|
| CMRR | Common-mode noise rejection — critical for coherent SNR | >25 dB (BPD480); ~30 dB (BPD570) |
| Bandwidth | Demodulation rate, OCT scan speed, pulse width | 10 MHz–400 MHz (BPD465); up to 1 GHz (BPD480) |
| Wavelength | Must match laser and fiber band | 1550 nm sensing/OCT; 1000–1700 nm (BPD480 InGaAs) |
| Input coupling | Fiber sensing vs benchtop interferometer | FC/APC or FC flange (fiber); spatial (BPD230) |
| Detector type | PIN for moderate power; APD for weak signals | PIN balanced (BPD465/480/DAS-BPD); APD balanced (BPD570) |
| Integration level | Discrete BPD vs turnkey receive module | Module (BPD series) or integrated CD-DVS/DAS-X |
Frequently Asked Questions
- When do I need a balanced photodetector instead of a single PIN or APD?
- Use a BPD when your measurement relies on the difference between two optical paths — coherent DVS/DAS demodulation, heterodyne beat detection, OCT interferometry or wind lidar — and common-mode laser noise must be cancelled. For simple power monitoring, choose PIN or APD single-ended modules.
- DAS-BPD vs BPD465 — which for fiber sensing?
- DAS-BPD is specifically tuned for distributed acoustic sensing coherent detection applications. BPD465 is a versatile 10 MHz–400 MHz fiber-coupled balanced detector also used in OCT, general fiber sensing and wind radar — confirm bandwidth and coupling with your demodulation scheme.
- What is CMRR and why does it matter?
- Common-mode rejection ratio (CMRR) quantifies how well matched photodiodes cancel identical signals on both inputs. Higher CMRR improves SNR in coherent detection where the differential signal can be small relative to laser RIN and drift.
- Can BPD modules integrate with YB Photonics DAS systems?
- Yes — DAS-BPD and CD-DVS/DAS-X are designed for coherent DVS/DAS receive paths. See DAS modules & systems and sensing DAQ cards for complete system building blocks.