Two-dimensional photonic crystal Mach–Zehnder interferometers

Abstract

Mach-Zehnder interferometers were fabricated from suspended membrane photonic crystal waveguides. Transmission spectra were measured and device operation was shown to be in agreement with theoretical predictions. © 2004 American Institute of Physics. ͓DOI: 10.1063/1.1642758͔ Planar photonic crystal waveguide ͑PCWG͒ technology has the potential to be a fundamental building block for future optical integrated circuits. Some of this potential arises from the ability to form small turning radius waveguide bends and wide angle Y branches 1 leading to the possibility of dense device integration. There have been many experimental demonstrations of two-dimensional photonic crystal waveguides recently including quantitative optical loss measurements.2-4 However, there have been few demonstrations published to date of photonic crystal waveguide bends and branches. [5][6][7] In this letter, we report on a demonstration of Mach-Zehnder interferometers formed in twodimensional photonic crystals.In this work we have fabricated Mach-Zehnder interferometers in two-dimensional photonic crystals with a range of path length differences between the arms of the interferometer. We expect therefore that the intensity transmitted through the interferometers will exhibit oscillations in the transmitted intensity as a function of the optical frequency with a period that depends on the path length difference and the propagation coefficient. The finite element method was used to calculate the band structure of the even guided mode for the PCWGs. Figure 1͑a͒ shows the calculated dispersion relations of guided modes of waveguides with ratios of the hole radius to lattice constant, r/a, of 0.27, 0.30, and 0.33. Only the lowest order guided mode is included in this figure. In this work, we intend to operate the fabricated MachZehnder interferometers in the spectral region in which there is very little chromatic dispersion. This simplifies the data analysis because we expect a fixed propagation coefficient and therefore a fixed oscillation period in the transmitted intensity over the wavelength range of operation. From the data in Fig. 1͑a͒, for an r/a value of 0.3 and a lattice constant value of 420 nm, this low chromatic dispersion region corresponds to the wavelength range of 1500-1550 nm and propagation coefficient in the range of 0.30-0.35. The experimental data in each case was taken in this low chromatic dispersion region. The group index can be obtained by differentiating the dispersion relation in Fig. 1͑a͒ and is plotted as a function of normalized wavelength in Fig. 1͑b͒ APPLIED PHYSICS LETTERS

2D Photonic crystal thermo-optic switch based on AlGaAs/GaAs epitaxial structure

“…A Mach-Zehnder interferometer operating successfully (in a purely passive manner) with an estimated 28% overall transmission using W1 channel waveguide was reported in [1]. An asymmetric Mach-Zehnder structure designed using a coupled-resonator W1 channel PhC waveguide has been reported [2] and another asymmetric PhC Mach-Zehnder structure was reported in [3], showing comparisons between different devices where the relative length of the arms of the Mach-Zehnder interferometer was changed.…”

Design and Modeling of WDM Integrated Devices Based on Photonic Crystals

“…As mentioned before, PCs have gained great interest due to the availability of high density integrated optical circuitry (Joannopoulos et al, 2008;Yanik et al, 2004;Niemi et al, 2006;Koshiba, 2001;Fasihi & Mohammadnejad, 2009a, 2009bMekis et al, 1999;Loncar et al, 2000;Martinez et al, 2003;Shin et al, 2004;Yanik et al, 2003). PC waveguides provide an efficient means of guiding light by allowing the realization of sharp optical bends (Mekis et al, 1996).…”

Genetic-Algorithm Assisted Design of C-Band CROW-Miniaturized PCW Interleaver

“…The black boxes highlight the optimized rods. (12) so that the result can be written as (13) Finally, (13) are plugged into the equations for and obtained from the first two rows of the matrix. The final equations describing the ring-coupler device are thus obtained as follows: (14) Once the building blocks are optimized and their -matrices are known, it is possible to calculate the full transfer function through matrix algebra by combining the matrix of the 50/50 coupler with the matrix of the MZI.…”

“…Interleavers can be realized with optical delay-line circuits employing directional couplers and Mach-Zehnder interferometers (MZIs) [10]- [13], while the filter architecture can be designed in either of two categories, the simplest one being a finite-impulse response (FIR) configuration based on delay lines and directional couplers [7], to which feedback loops such as ring resonators can be added to obtain an infinite-impulse response (IIR) configuration [14]. The interest of this work is the design of a miniaturized interleaver with flat-top passbands, for integration in PC circuits.…”