The **LPD-31P2-R** is a high-performance **InGaAs (Indium Gallium Arsenide) PIN Photodiode** module, typically integrated with a fiber pigtail. It is primarily designed for high-speed optical communication systems and fiber optic sensing. --- ### ## Technical Specifications The following table highlights the core electronic and optical characteristics of the LPD-31P2-R: | Parameter | Typical Value | Unit | | :--- | :--- | :--- | | **Spectral Response Range** | 1100 to 1650 | nm | | **Responsivity** | 0.85 – 0.90 | A/W (@1310/1550nm) | | **Dark Current** | 0.1 – 0.5 | nA | | **Capacitance** | 0.45 – 0.7 | pF | | **Bandwidth (-3dB)** | 2.0 – 3.0 | GHz | | **Reverse Voltage (Max)** | 20 | V | | **Operating Temperature** | -40 to +85 | °C | --- ### ### Key Electronic Components & Features 1. **InGaAs Photosensitive Chip**: The heart of the device is the InGaAs chip, which is optimized for the second and third optical windows (1310nm and 1550nm). It converts incoming photons into an electrical current (photocurrent). 2. **Low Capacitance Structure**: With a capacitance typically below 1pF, the part minimizes RC delay, allowing for high-speed data reception (up to several Gbps). 3. **Low Dark Current**: The "Dark Current" refers to the residual current that flows through the photodiode even when no light is present. At <0.5nA, this part ensures a high Signal-to-Noise Ratio (SNR). 4. **Package Construction**: * **Pigtail Interface**: Usually features a G652 or G657 single-mode fiber. * **Receptacle/Plug**: The "R" in the suffix often denotes a **Receptacle** style or a specific **RoHS** compliance/Rotation orientation depending on the manufacturer's internal coding (commonly associated with brands like LightPower or similar optoelectronic vendors). --- ### ### Typical Application Circuit When integrating the LPD-31P2-R, it is usually paired with a **Transimpedance Amplifier (TIA)** to convert the small photocurrent into a measurable voltage. ```python # Conceptual Electronic Flow [Optical Fiber] -> [LPD-31P2-R Photodiode] -> [TIA Amplifier] -> [Post-Amp/Limiting Amp] ``` ---