Wavelength switching technique for phase interrogation of Mach Zehnder interferometer-based optical sensors.

A method for determining the phase shift of a Mach Zehnder interferometer (MZI) is presented. It is based on switching the wavelength of continuous wave (CW) laser light illuminating the MZI and measuring the interferometer output amplitudes at DC and switching frequency. The method can measure the MZI phase shift unambiguously over the entire phase shift range of 2π.

Mach-Zehnder modulator condition for a low chirp factor versus DC bias.

An analysis of the Mach-Zehnder modulator's chirp factor versus DC bias is presented. Unlike the well-known belief that is infinite at 0 and biases, it is shown that can be zero at these biases under a careful balance of the modulations in the two modulator arms. Derivation of the condition to achieve this effect is given, and practical verifications are presented, where an excellent agreement with the theory is obtained.

Characterization of optical Mach-Zehnder modulator using DC measurements.

This Letter presents a simple but effective method for characterizing the frequency response of broadband Mach-Zehnder optical modulators. The method measures the modulator's direct current output versus the modulating frequency to determine the frequency response and requires no calibrated broadband photodetector or measurements of the electrical or optical spectrum or radio frequency power. Therefore, it significantly simplifies characterization.

Amplitude independent instantaneous frequency measurement using all optical technique.

A novel all-optical system which independently measures both the amplitude and frequency of an RF signal is proposed and demonstrated. A photonic Hilbert transformer provides two orthogonal measurements of an RF signal. These are compared using four wave mixing in a highly nonlinear fiber, producing two independent outputs enabling determination of both signal frequency and amplitude.

Remoted all optical instantaneous frequency measurement system using nonlinear mixing in highly nonlinear optical fiber.

A novel remoted instantaneous frequency measurement system using all optical mixing is demonstrated. This system copies an input intensity modulated optical carrier using four wave mixing, delays this copy and then mixes it with the original signal, to produce an output idler tone. The intensity of this output can be used to determine the RF frequency of the input signal.

Instantaneous frequency measurement system using optical mixing in highly nonlinear fiber.

A broadband photonic instantaneous frequency measurement system utilizing four-wave mixing in highly nonlinear fiber is demonstrated. This new approach is highly stable and does not require any high-speed electronics or photodetectors. A first principles model accurately predicts the system response.

Wideband RF photonic in-phase and quadrature-phase generation.

A photonic implementation of a practical broadband RF Hilbert transformer is demonstrated by using a four-tap transversal system. An almost ideal 90 degrees phase shift with less than 3 dB of amplitude ripple has been achieved from 2.4 to 17.

Multichannel vector sum phase shifter.

A novel multichannel vector sum phase shifter that is suitable for phased array antenna applications is demonstrated. Each channel is implemented using a distinct optical wavelength. Selective control of each channel is performed using an acousto-optic polarization coupler.