Integrated-optical Mach–Zehnder add–drop filter fabricated by a single UV-induced grating exposure

Abstract

A four-port bandpass filter is demonstrated with good performance by use of UV-induced Bragg gratings in P-doped channel waveguides without UV trimming. The simple, single-step fabrication procedure is experimentally and theoretically analyzed, and tolerances are calculated for achieving practical wavelength-division-multiplexed communication system performance.

Design considerations in optical add/drop multiplexers based on grating-assisted null couplers

“…6. The total electric field in the grating region can be expressed as (3) where are the transverse field distributions and are the propagation constants of the ortho-normal eigenmodes at the coupler waist. The perturbation in the relative dielectric permittivity can be expressed, in terms of its spatial harmonics, as (4) where is the period of the perturbation.…”

Novel full-cycle-coupler-based optical add-drop multiplexer and performance characteristics at 40-Gb/s WDM networks

“…4). In this case, the grating length can be expressed as (9) and taking into account that leads to the exact relation (10) which will be referred to as the "grating length equation" from now on, because it relates the grating length to its own characteristics (through ) as well as the coupler characteristics (through and ).…”

<title>Design and simulation of a new planar OADM component</title>

“…If the input light is far from Bragg wavelength, it will transfer from the input terminal of waveguidel, passing through the waveguide2, to the output terminal of the waveguide3. Near the Bragg wavelength, the grating frustrated effect is induced [8]. The output of the waveguidel operates as the drop port, and the input of the waveguide3 operates as the add port.…”

“…Besides, the complex fabrication processes also attributed to their high unit cost. The other design is a Bragg grating-assisted Mach-Zehnder interferometer-based OADM [5,6]. Two grating have to be placed precisely on the related positions of the Mach-Zehnder interferometer.…”

“…Near the Bragg wavelength, within the spectral region known as the stop band, the grating has two effects: first, it introduces a strong dispersion making the coupler asynchronous (phase mismatched); second, it creates a barrier (a one-dimensional photonic band gap) that rejects photons attempting to tunnel through. With proper design parameters, a grating-frustrated directional coupler can be used as an all-fiber channel-dropping filter [8]. Based on the above concept, the construction of a gratingfrustrated based OADM is feasible.…”