Applying a reverse bias increases the width of the depletion junction producing an increased responsivity with a decrease in junction capacitance and produces a very linear response. The current measured through the circuit indicates illumination of the device the measured output current is linearly proportional to the input optical power. In photoconductive mode, an external reverse bias is applied, which is the basis for our DET series detectors. Mode selection depends upon the application's speed requirements and the amount of tolerable dark current (leakage current). Photovoltaic)Ī photodiode can be operated in one of two modes: photoconductive (reverse bias) or photovoltaic (zero-bias). The responsivity of a photodiode can be defined as a ratio of generated photocurrent (I PD) to the incident light power (P) at a given wavelength: Depicted in Figure 1 is a junction photodiode model with basic discrete components to help visualize the main characteristics and gain a better understanding of the operation of Thorlabs' photodiodes.įigure 1: Photodiode Model Photodiode Terminology It is necessary to be able to correctly determine the level of the output current to expect and the responsivity based upon the incident light. A photodiode is a fast, highly linear device that exhibits high quantum efficiency and may be used in a variety of different applications. Click here to learn more.Ī junction photodiode is an intrinsic device that behaves similarly to an ordinary signal diode, but it generates a photocurrent when light is absorbed in the depleted region of the junction semiconductor. Thorlabs offers spectral-flattening filters that are designed to improve the response uniformity of our silicon photodiodes. This can be accomplished by placing a focusing lens or pinhole in front of the detector element. Thorlabs therefore recommends that the incident light on the photodiode is well centered on the active area. Inhomogeneity on the edge of an active area of the detector can generate unwanted capacitance and resistance that distorts the time-domain response of a photodiode. The Photodiode Tutorial provides more general information regarding the operation, terminology, and theory of photodiodes. With zero bias (Photovoltaic Mode), the NEP is specified by the thermal noise only, which is caused by the shunt resistance of the photodiode. For example, the Noise Equivalent Power (NEP) as a Function of Temperature section provides background on NEP values specified by shot noise and thermal noise. This tab also outlines the theory and methods we use to define the specifications of our photodiodes. Many of our photodiodes can be reverse voltage biased using the PBM42 DC Bias Module for faster speed and higher optical power detection.įor information on the photodiode saturation limit and the noise floor, as well as a collection of Thorlabs-conducted experiments regarding spatial uniformity (or varying responsivity) and dark current as a function of temperature, refer to the Lab Facts tab. We also offer calibrated photodiodes, which come with with NIST-traceable calibration, to correct for the differences in responsivity. Please note that the PDs sold below are not calibrated, meaning responsivity will differ slightly from lot to lot refer to the Response Variation tab for more information. To complement our photodiode product line, we offer mounted photodiodes and a range of compatible photodiode sockets. The DSD2 is a dual-band photodiode, which incorporates two photodetectors sandwiched on top of each other (Si substrate on top of an InGaAs substrate), offering a combined wavelength range of 400 to 1700 nm. The FD10D and FD05D are InGaAs photodiodes with high responsivity from 900 to 2600 nm, allowing detection of wavelengths beyond the normal 1800 nm range of typical InGaAs photodiodes. Alternatively, the FD11A Si photodiode has a dark current of 2 pA, making it our photodiode with the lowest dark current. The FDS015 Si photodiode has a 35 ps rise time and a 0.65 pF junction capacitance, making it the highest speed, lowest capacitance photodiode offered below. Our fastest photodiodes are the FDS015, FDS02, and FDS025 Si photodiodes. Germanium (Ge) photodiodes, which are based on an N-on-P structure, are also available. Discrete PIN junction photodiodes include indium gallium arsenide (InGaAs) and silicon (Si) materials. Thorlabs stocks a wide selection of photodiodes (PD) with various active area sizes and packages. FDS100 Si Photodiode Also Available in Packs of 5, 10, or 50.Si, InGaAs, Ge, and Dual Band (Si/InGaAs) Unmounted Photodiodes Available.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |