Compare Model Drawings, CAD & Specs Spectral Range Maximum Measurable Power1 Minimum Measurable Power2 Availability Price
918d calibrated photo diode power sensor
Optical Power Detector, InGaAs, 800-1650 nm, OD1 Attenuator
$1,504.83
In Stock
800 - 1650 nm 100 mW 20 pW
In Stock
918d calibrated photo diode power sensor
Optical Power Detector, InGaAs, 800-1650 nm, OD2 Attenuator
$1,462.60
In Stock
800 - 1650 nm 1000 mW 20 pW
In Stock
918d calibrated photo diode power sensor
Optical Power Detector, InGaAs, 800-1650 nm, OD3 Attenuator
$1,263.81
In Stock
800 - 1650 nm 2000 mW 20 pW
In Stock
918d calibrated photo diode power sensor
Optical Power Detector, Germanium, 780-1800 nm, OD1 Attenuator
$856.96
In Stock
780 - 1800 nm 100 mW 5 nW
In Stock
918d calibrated photo diode power sensor
Optical Power Detector, Germanium, 780-1800 nm, OD2 Attenuator
$925.97
In Stock
780 - 1800 nm 1000 mW 5 nW
In Stock
918d calibrated photo diode power sensor
Optical Power Detector, Germanium, 780-1800 nm, OD3 Attenuator
$775.59
In Stock
780 - 1800 nm 2000 mW 5 nW
In Stock
918d calibrated photo diode power sensor
Optical Power Detector, Silicon, 400-1100 nm, OD1 Attenuator
$726.15
In Stock
400 - 1100 nm 40 mW 20 pW
In Stock
918d calibrated photo diode power sensor
Optical Power Detector, Silicon, 400-1100 nm, OD2 Attenuator
$785.89
In Stock
400 - 1100 nm 400 mW 20 pW
In Stock
918d calibrated photo diode power sensor
Optical Power Detector, Silicon, 400-1100 nm, OD3 Attenuator
$664.35
In Stock
400 - 1100 nm 2000 mW 20 pW
In Stock
918d calibrated photo diode power sensor
UV Silicon Detector, 200-1100 nm, OD3 Attenuator
$791
In Stock
200 - 1100 nm 200 mW 20 pW
In Stock

Specifications

Features

Excellent Photodiode Linearity

These photodiodes show excellent linearity over a large dynamic range. This is ideal for use in applications that require high accuracy measurements down to the pW level, especially when combined with a high sensitivity power meter that can accommodate the large dynamic range of the optical signal.

Responsivity Variation over Temperature

A natural characteristic of a photodiode is for the its optical response to change as the temperature changes near the bandgap of semiconductor materials. Newport’s 918D series sensors feature a thermocouple near the photodiode, which allows certain Newport meters to read the temperature and automatically adjust the responsivity, ensuring the most accurate measurements.

Factors that Affect Maximum Measurable Power

The maximum measurable power of photodiode sensors is dependent on several factors such as the wavelength of incoming light, photodiode current output saturation, temperature, use of an attenuator and a power meter's maximum current input value. Newport provides maximum power specifications based on the power meter models, with and without an attenuator, and wavelength-dependent maximum power level. With these factors affecting measurable power in mind, choosing the proper detector for your application is critical.

Attenuator On/Off Sensor

The attenuator on/off sensor is built into the detector head. When a 918D series detector is connected to power meter models 1936-R, 2936-R, 1919-R, 841-PE-USB, and the 1830-R series, the meter automatically switches the responsivity value. The user does not need to update the power meter setup. The detector is calibrated with the integrated attenuator and without it, and the data is saved in the EEPROM. 

Wide Dynamic Range with OD3 Attenuator

The 884 Series OD3 attenuators extend the calibrated optical dynamic range of our detectors by three decades. Both the attenuator and detector have their serial number scribed on the part which, to maintain calibration, must match. Our attenuator design provides high damage threshold and spectral flatness. With the low noise equivalent power (NEP) associated with the photodiodes being used, a wider dynamic range is achieved. The clear aperture of the 884 Series attenuators is 10.3 mm.

NIST-traceable Sensor Calibration

Our calibrated photodiode sensors include a full spectral response calibration utilizing NIST-traceable standards calibrated with high-precision equipment maintained in Newport’s optical detector calibration facility. Tight calibration facility and process control allows the tightest calibration uncertainty in industry. Each detector is shipped with the calibration data, which is electronically stored inside the detector's EEPROM. A certificate of calibration as well as the actual calibration curves and data are shipped with each detector for attenuator and no attenuator models. To maintain accuracy and guarantee performance, Newport recommends annual photodiode detector calibration.

Detector calibration system block diagram.

Internal Temperature Sensor

The internal temperature sensor on the detector head is used to compensate the responsivity drift caused by the temperature change in the photodiode. The responsivity change is most sensitive around the bandgap, or towards the longer wavelength limit. The power meter calculates the temperature and automatically updates the responsivity value so that the measurements remain accurate. This feature is enabled with the power meter models 1936-R, 2936-R, 1919-R, and 841-PE-USB.

Photodiode Sensor Physics

A photodiode consists of a semiconductor p-n junction similar to a laser diode and LED However, the fundamental radiation process involved is absorption. Light falling on the junction causes the formation of electron-hole pairs. In photovoltaic mode, the electron-hole pairs migrate to opposite sides of the junction, thus producing a voltage. One critical difference between a semiconductor photon source and a photon detector is that the former requires the use of a direct-gap semiconductor while the latter can utilize an indirectgap semiconductor. While the simultaneous requirement for energy and momentum conservation makes photon emission much less likely in indirect-gap semiconductors, this is not the case for absorption. A readily-achievable two-step process occurs where an electron is excited to a high level in the conduction band followed by a relaxation process where its momentum is transferred to phonons. Since this process can be sequential, it is much more likely than an emission process where the two steps must occur simultaneously. Please see our Photodiode Sensor Physics technical note for additional information.

Adapters for Fiber-Optic Applications

These photodiode sensors can be converted to measure optical power from connectorized or bare optical fibers. Newport offers a comprehensive set of screw-in fiber-optic adapters to match a variety of connector types. Our bare fiber holder and adapter mount are designed together to hold 250-µm bare fibers without damaging the fiber.

Compatible Power Meters

Newport offers a comprehensive range of optical power meters from low cost, hand-held meters to the most advanced dual-channel benchtop meter available in the market. Presented here is a list of meters compatible with the 918D Series sensors. For more detailed information about our power meters, please see our Optical Power Meter Guide.

2936-R-grey_sensor

1936-R/2936-R

1830_Front_10_586

1830-R

1919-R_angle

1919-R 

843-R_side

843-R

841-PE-USB

841-PE-USB
Temperature Sensing     
Automatic Attenuator Sensing  
Measurement Modes

Power

Peak-to-Peak Power

RMS Power

Power

Power

Exposure

Power Power 
Analog Bandwidth Up to 400 kHz Up to 20 kHz  15 Hz  15 Hz 15 Hz 
Data Storage 250,000 pts internal   Limited by USB memory size

843-R-USB: Via PMManager

843-R: None

Via PMManager
Measurement Rate per Second 10,000 20 15 15 15 
Trigger In/Out
Computer Interface

USB

RS-232

USB

RS-2321

GPIB1

USB

RS-232

843-R-USB: USB

843-R: None
USB

Only available with model 1830-R-GPIB

Additionally, please refer to Newport Power Meter and Detector Legacy and Compatibility for a complete list of meters that are compatible with this model.