Next generation radar system desires frequency agile low phase noise local oscillator signal. A rapidly tunable multiloop optical frequency locked loop (OFLL) can provide such functionality. The OFLL employs a pair of electro-optic tunable microchip lasers that are heterodyned to produce a frequency agile microwave modulated optical subcarrier. A feedback through a multiloop fiber optic based microwave frequency discriminator assures low phase noise operation. This paper concerns design and optimization of stable, low phase noise OFLLs. This paper features a parametric study, followed by proof-of-concept experiments. Phase noise of −120 dBc/Hz at 10 KHz offset is achieved experimentally and conditions for obtaining a phase noise in excess of −130 dBc/Hz are discussed.
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