Generalized Mach-Zehnder Interferometer Research Articles

Generalized Mach–Zehnder interferometers for sensing applications

A sensing application of integrated optical (IO) generalized Mach–Zehnder interferometers (GMZIs) is proposed. GMZIs are multiple-arms Mach–Zehnder interferometers (MZIs) and are widely used in optical telecommunications for wavelength-division multiplexing (WDM) and optical switching. In this paper, we show that GMZIs can be used in order to realize highly sensitive IO refractometers that can be usefully employed in chemical and biochemical sensing applications. These devices, with a suitable design, permit sensitive operation over a wide range of indices without the ambiguities of conventional MZIs. Furthermore, in some applications a direct digital readout is possible.

Logarithmic wavelength demultiplexers

A general approach for a full 1 × N demultiplexer using a tree of filter stages is proposed. The device architecture is compact, requiring at least N - 1 filter stages, and flexible, as each filter stage can be arbitrarily designed, with the only constraint of the half-band power property. The filters can be realized using any optical filtering techniques as thin-film interference, Bragg gratings, or planar delay-line circuits. The performances of the proposed architecture are illustrated with respect to different lattice-form finite impulse response (FIR) and infinite impulse response (IIR) filter stages, showing that the demultiplexer inherently presents low crosstalk and flat passband. A design example of a 1 × 4 demultiplexer consisting of three all-pass (AP) filters is compared with a generalized Mach-Zehnder interferometer (MZI) with four AP filters in its arms, showing that the two approaches achieve similar results.

Theory of variable-ratio power splitters using multimode interference couplers

In this letter, we analyze the integrated optical N/spl times/N generalized Mach-Zehnder interferometer (GMZI) employing multimode interference (MMI) couplers. A transfer matrix is used to derive analytic expressions for the intensity distribution at the output ports of the GMZI as a function of the phase shifts applied to the arms. These expressions form a system of nonlinear equations which are numerically solved for the phase shifts, enabling a new interpretation of the GMZI as a variable-ratio power splitter. The performance of the GMZI has been simulated, and it is found that the power splitting ratio is tolerant to both the accuracy of the applied phase shifts and to fluctuations in wavelength.

Analysis of generalized Mach-Zehnder interferometers for variable-ratio power splitting and optimized switching

The nonideal integrated optical N/spl times/N generalized Mach-Zehnder interferometer (GMZI) employing multimode interference (MMI) couplers is analyzed using transfer matrix techniques. Deviations in the phase relations and the power splitting ratio of the MMI couplers are included in the theory, along with the effects of phase errors in the interferometer arms. The predictions of the theory are compared to the response of a 4/spl times/4 GMZI which has been fabricated. The device is operated as both a variable-ratio power splitter and a switch by compensating for the phase errors in the interferometer arms, but the performance is ultimately limited by the nonideal imaging in the MMI couplers. The practicality of these applications is investigated by performing a tolerance analysis for the operation of 1/spl times/N power splitters and switches for N up to 10.