Frequency Domain Detectors

The DG-15ir and DG-15xr photodetectors are specifically designed to be analog, frequency-domain detectors for communications applications where a flat frequency response ( ±1 dB) from DC-20 GHz is required. The DG-15ir is specifically optimized for the 950-1650nm spectral range with single-mode fiber input, while the DG-15xr provides the same DC-20 GHz performance with 700-1650nm spectral coverage and multi-mode fiber input. These units are also battery powered, and fully self-contained.

Microwave applications typically benefit from this type of frequency response, where the responsivity of the detector must remain constant over the entire usable 20 GHz band. These models have the same basic performance as the D-15ir (29 GHz opt bandwidth) except that the frequency response shape has been flattened to 20 GHz. As a result of this frequency response shape, the pulse or time-domain performance is compromised resulting in a pulse that rings slightly (see plots and application note).

As with all the D-Series communications detectors, the detector element is optimized for maximum responsivity and the optical return loss is better than 30 dB with a single-mode fiber input on the DG-15ir and 14 dB with multimode fiber on the DG-15xr. Output termination is fixed at 50 ohms for low reflection (VSWR) performance.