Jw Pedersen

A new short and low-loss passive polarization converter on InP

We propose an improved polarization converter in InGaAsP-InP. It contains a series of waveguide sections with asymmetric cross-sections with angled facets. A 09-mm-long TE/TM-converter at a wavelength of 1.5 /spl mu/m is simulated. It contains 10 sections and has an excess loss of 0.25 dB. Both coupled mode theory and beam propagation method (BPM) simulations are included.<<ETX>>

A short polarization splitter without metal overlays on InGaAsP-InP

A new and very short polarization splitter on InGaAsP-InP is designed and realized for the first time. The component contains a ridge waveguide directional coupler of 0.4 mm length and an output section of 0.7 mm. It uses the large waveguide birefringence of the first-order TE and TM modes to obtain polarization selective directional coupling. In this way, additional metal layers on the waveguides to create birefringence are avoided and fabrication becomes very simple. Components are realized, which show splitting ratios close to -20 dB. Excess losses are below 1 dB. The polarization splitting is investigated in the wavelength region of 1525-1560 nm and found to be better than -9 dB.

A compact integrated InP-based single-phasar optical crossconnect

The first integrated InP-based polarization independent optical crossconnect is reported. The device can crossconnect signals at four wavelengths independently from two input fibers to two output fibers. Total on-chip loss is less then 16 dB. Device size is 7/spl times/9 mm/sup 2/.

Mode evolution type polarization splitter on InGaAsP/InP

A new type of mode-evolution polarization-splitter based on InGaAsP/lnP has been designed and realized. The component uses the large waveguide birefringence of the first-order TE and TM modes in a ridge waveguide made in a heterostructure, In the input section an asymmetric Y-junction acts as a mode converter in order to inject first-order TE- and TM-modes in a polarization-splitting section, which consists of a Y-junction formed by a bimodal and a monomodal waveguide. In the output section a third Y-junction is connected to the bimodal waveguide to couple the first-order mode to a monomodal output waveguide. Components that are 6-mm long and show polarization splitting at a wavelength of 1.55 mu m have been realized. The best splitting ratios are close to -20 dB, which is in agreement with BPM simulations. Excess losses are below 1 dB.<<ETX>>

Realization of a short integrated optic passive polarization converter

For the first time, passive polarization converters with lengths of less than 1 mm and high polarization conversions are realized on InGaAsP-InP. Angled facets in a periodic coupler are used to obtain efficient conversion. Polarization conversions of more than 70%, respectively more than 90%, are measured for two different realizations of the angled facets. The most promising technology used in the realization results in a propagation loss of less than 1 dB/mm for both polarizations.<<ETX>>

Chirping of an MMI-PHASAR demultiplexer for application in multiwavelength lasers

We report the first chirped multimode interference-based phased-array (MMI-PHASAR) for application in multi-wavelength lasers (MWLs). To avoid wavelength ambiguity in MWLs, undesired orders are suppressed by chirping the array of arms in the demultiplexer. Simulations show that a suppression of adjacent orders of more than 2 dB can be achieved. A 1/spl times/5 MMI-PHASAR has been realized in which the effect of the chirping is clearly visible according to the simulations.

Sharp vertices in asymmetric Y-junctions by double masking

A novel fabrication procedure is presented for the realization of sharp vertices in Y-junctions on InGaAsP/InP. Overlapping masking layers of silica and resist respectively define the two branches in the junction. A nearly perfect branching point is made by a reactive ion etch with two overlapping mask strips. An asymmetric Y-junction designed to function as a mode splitter is realized with this technique. It shows an improvement of 4-8 dB in mode splitting over a version made with a single masking layer. This agrees with BPM-simulations on the effect of blunting in these Y-junctions.<<ETX>>

Loss-reduction of deeply etched InP/InGaAsP waveguides by CBE regrowth

Low-loss waveguides are the basic components in photonic integrated circuits (PICs). A high degree of integration can only be obtained by the use of small components. In general the size of optical components can be reduced by increasing the optical contrast. The maximum contrast in a ridge waveguide structure can be achieved by etching through all the waveguiding layers. Recently, it has been shown [1] that, the size of MMI-couplers and bends can be significantly reduced by the application of this deep etch technology. In addition, device performance of deeply etched waveguides is insensitive to etch depth variations.

New approach to polarization-independent integrated optical circuits: the bimodal polarization converter

Integrated optical circuits have to operate in a fiber network that does not preserve the polarization state. Therefore operations in the network should be polarization independent. In order to support both polarizations compromises are often made in design and realization. Such compromises can be avoided when incoming light of arbitrary polarization is converted into two identically polarized modes of different mode order. This is done with a passive bimodal polarization converter (BPC), which can be integrated in the circuit. The BPC is especially useful in combination with components that process both modes simultaneously (detectors, phased-array demultiplexers, multimode interference couplers, etc.) and for use with monomodal circuits mode splitters, e.g. asymmetrical Y-junctions, that enable separate processing of the modes. Design and simulations of the converter are performed for an InP/InGaAsP/InP heterostructure with a quaternary layer band gap of 1.3 /spl mu/m. Coupled-mode expressions show that with 13 sections complete conversion is obtained with low loss (0.3 dB).

Wavelength insensitive compact bimodal polarisation converter on InP

First realisation of a compact, wavelength independent passive bimodal integrated optical circuit polarisation converter with large conversion per junction is reported. Maximum polarisation conversion of 85% is measured at λ=1.5 μm. Wavelength insensitive operation is measured in the whole EDFA-window.