This project aims to develop an advanced photodiode concept able to overcome the power handling limitations of a standard photodiode. Advanced packaging concepts are proposed for heat dissipation and cooling of the photodiode chip and for efficient light coupling to the active photodiode area. Preliminary environmental testing, such as gamma and proton irradiation testing, are conducted to identify the suitability of the technology platform for space born applications.
Operation of a photodiode under high optical input power is challenging. First, because the optical induced space charge effects limits the O/E performance such as the RF output power and linearity of the device. Second, due to the high photocurrent and elevated bias voltage the dissipated power within the device increases which may lead to thermally induced damage.
The product has been implemented on an advanced photodiode structure able to operate at high optical input power under moderate bias voltage suppressing optical induced space charge effects. The photodiode has been flip-chip mounted on a high thermal conductivity AlN carrier which allows to increase the damage threshold from typically 160mW for a standard photodiode to over 500mW dissipated power (photocurrent x voltage). Under operation condition, this reduces the device temperature which is beneficial in terms of O/E performance and reliability of the device.
An advanced high power, hermetically packaged photodiode module has been developed. The optical input is supplied through a single-mode 9/125um fiber pigtail with FC/APC connector. The detector incorporates an internal bias-T and an electrical RF K-connector output.
The device operates from low optical input power of -20dBm up to +20dBm offering an extremely large dynamic range. Two versions of the product have been implemented, a broad band matched module with a -3dB bandwidth above 22GHz and a narrow band module optimized at 19GHz operation frequency. The broad band module generates up to +12dBm RF output power with an optical saturation photocurrent of 25mA while the narrow band module offers +15dBm RF output power at 19GHz with an optical saturation current of 30mA. Both devices generate a highly linear output signal, up to +26dBm OIP3 which enables operation of analogue photonic links with low signal distortion.
Preliminary Gamma and Proton Irradiation test results show promising results and demonstrate the potential for the Albis technology platform for space born applications.
The first phase included a review of materials, technologies and concepts for the implementation of the photoreceiver, the sub-assembly and the package (PDR, MS1).
In the second phase, specific test structures have been developed and manufactured, which allowed to develop a more detailed and accurate electrical and thermal simulation model and to create a detailed design. (DDR, MS2).
In the third phase, the high power photodiode chip, sub-assembly and assembly have been manufactured and tested according to the test plan (TRB, MS3).
The conclusion of the project has been presented in the final review meeting (FR, MS4, MS1-CCN).
The final review (FR) of the project has been successful and all deliverables accepted.