60-GHz low-phase noise optical-electrical oscillator using newly developed high-power photoreceiver module

We report an optical–electrical (OE) oscillator using two new key components (a high-power integrated photoreceiver module and a low-driving-voltage lithium niobite (LN) Mach–Zehnder modulator (MZM)) to configure key parts of the entire OE oscillator system. A 60-GHz narrowband photoreceiver module integrated with a 60-GHz photodetector chip with a gain emphasis circuit and a 60-GHz high-power amplifier chip was designed and fabricated. By increasing the input photocurrent to 5 mA at 60 GHz, we successfully achieved a 1-dB power compression level of +16 dBm with good output linearity. The LN-based bulk MZM was specially designed to decrease the driving voltage to 1.5 V by optimizing both the waveguide and electrode length at high frequencies. Excellent performance with a -5 dB insertion loss at 60 GHz was achieved. The OE oscillator system was configured via a feedback loop using optical and electrical components, which primarily consisted of the newly developed photoreceiver and MZM through a 100 m–1 km long optical fiber. We successfully demonstrated -106 dBc/Hz at a 10-kHz offset near 60 GHz. The design and fabrication of the OE system are discussed in detail herein.