High-performance photodetectors (HPPDs), with high output power and bandwidth, are needed for RF photonics links. Applications for these HPPDs range from high-power remote antennas, low-duty-cycle RF pulse generation, linear photonic links, high dynamic range optical systems, and radio-over-fiber (ROF). Freedom Photonics is a manufacturer of high-power photodetectors (HPPD) for the 1480 to 1620nm wavelength range, now being offered commercially. In 2016, Freedom has developed a HPPD for similar applications extending into the V-band. The basic device structure used for these photodetectors can achieve over 100-GHz bandwidths with slight variations. This work shows data for RF power and bandwidth performance for various size photodiodes, between 10 μm and 28 μm in diameter. Measurement data will be presented, which were collected at both assembly level and for fully packaged detectors. For detector devices with bandwidth performance over 50 GHz, the generated RF power achieved is expected to be over 15 dBm. This performance is exceptional considering the photodiode is fully integrated into a hermetic package designed for 65 GHz. Improvements in the coplanar waveguide (CPW) transmission line and flip-chip bonding design were integral in achieving the higher saturation at the higher bandwidth performance. Further development is required to achieve a >100 GHz packaged photodetector module.
A method of doping germanium using 1064 nm pulsed fiber laser was demonstrated. The secondary ion mass
spectrometry showed a p-n junction of 800 nm deep with a peak phosphorus concentration of 2×1019 cm-3. Germanium
photodiodes were fabricated on the laser-doped p-n junctions. Low bulk and surface leakage current values were
obtained which were comparable to diodes fabricated by rapid thermal diffusion. Laser doping allows low thermal
budget, minimization of surface desorption and selective doping without requiring photolithography. Laser doping was
shown to be an effective method for fabrication of electronic and optoelectronic devices.