Optically fed microwave true-time delay based on a compact liquid-crystal photonic-bandgap-fiber device

An electrically tunable liquid-crystal, photonic-bandgap-fiber-device-based, optically fed microwave, true-time delay is demonstrated with the response time in the millisecond range. A maximum electrically controlled phase shift of around 70 degrees at 15 GHz and an averaged 12.9 ps true-time delay over the entire modulation frequency range of 1-15 GHz are obtained.