Arrayed Waveguide Grating Multiplexer Research Articles

Novel Wavelength Multiplexer Using (N + 1) × (N + 1) Arrayed Waveguide Grating and Polarization-Combiner-Rotator on SOI Platform

We propose an ultra-compact novel wavelength multiplexer employing a ( N + 1) × ( N + 1) arrayed waveguide grating (AWG) and a polarization-combiner-rotator (PCR) on the SOI platform, to realize a multiplexing for 2 N wavelengths with a spacing of Δλ. The ( N + 1) × ( N + 1) AWG works at a bidirectional way to provide two groups of N × 1 wavelength multiplexing with each group having a channel spacing of 2×Δλ, and the central wavelengths of all input channels in one group have a wavelength shift of Δλ with respect to those in the other group. The double channel spacing results in a significant decrease on the footprint of the ( N + 1) × ( N + 1) AWG-based multiplexer compared with a conventional 2 N × 1 AWG multiplexer with the same wavelength spacing Δλ. Due to the fact that a single mode fiber is insensitive to the polarization of input light, if we consider short reach datacom applications such as 100/400 GbE, the two separate multiplexing outputs of the ( N + 1) × ( N + 1) AWG can be combined as one output with one half wavelengths working at TE polarization and the other at TM polarization by employing a low loss and broadband PCR. In the experiment, we demonstrate a 16 × 200 GHz multiplexer based on a 9 × 9 AWG. The experimental results show that the on-chip loss of the fabricated multiplexer is 2.7 dB and the loss uniformity is 0.5 dB. The 1-dB and 3-dB bandwidths are >0.56 nm (i.e., 35% of the wavelength spacing) and >1.1 nm (i.e., 69% of the wavelength spacing), respectively. They can also be further increased by decreasing the gap between adjacent input waveguides at the interfaces of star couplers of the designed AWG without inducing an excess loss. The proposed multiplexer has great potential for application to future super large capacity (> Tb/s) data transmission systems.

EML Array fabricated by SAG technique monolithically integrated with a buried ridge AWG multiplexer

We report the fabrication of a ten channel electroabsorption modulated DFB laser (EML) array. Different emission wavelengths of the laser array are obtained by selective area growth (SAG) technique, which is also used for the integration of electroabsorption modulators (EAM) with the lasers. An arrayed waveguide grating (AWG) combiner is integrated monolithically with the laser array by butt-joint regrowth (BJR) technique. A buried ridge waveguide structure is adopted for the AWG combiner. A self aligned fabrication procedure is adopted for the fabrication of the waveguide structure of the device to eliminate the misalignment between the laser active waveguide and the passive waveguide. A Ti thin film heater is integrated for each laser in the array. With the help of the heaters, ten laser emissions with 1.8nm channel spacing are obtained. The integrated EAM has a larger than 11dB static extinction ratios and larger than 8GHz small signal modulation bandwidths. The light power collected in the output waveguide of the AWG is larger than −13dBm for each wavelength.

Compact Hybrid-Integrated 100-Gb/s TOSA Using EADFB Laser Array and AWG Multiplexer

We have developed a compact hybrid-integrated four-lane $\times 25.8$ Gb/s transmitter optical sub-assembly (TOSA) for a 100 Gb/s transceiver for 40-km transmission. The TOSA has a simple configuration in which a four-channel electroabsorption modulator integrated distributed feedback (EADFB) laser array is directly attached to the input waveguide end-faces of a silica-based arrayed waveguide grating (AWG) multiplexer. We integrated a lateral tapered spot-size converter for the EADFB laser to achieve a high optical butt coupling efficiency between the EADFB lasers array and the AWG multiplexer. We confirmed that the TOSA, which is $19.9~\text {mm} \,\times \, 6~\text {mm} \,\times \, 5.8$ mm, achieved error-free operation for a 40-km transmission with a high average optical output power of over 0.3 dBm at an operating temperature of 55 °C.

Compact Hybrid Integrated 100-Gb/s Transmitter Optical Sub-Assembly Using Optical Butt-Coupling Between EADFB Lasers and Silica-Based AWG Multiplexer

A compact hybrid-integrated 100 Gb/s (4 lane × 25.78125 Gb/s) transmitter optical sub-assembly (TOSA) has been developed for a 100 Gb/s transceiver for 40-km transmission over a single-mode fiber. The TOSA has a simple configuration in which four electro-absorption modulator-integrated distributed feedback (EADFB) lasers are directly attached to the input waveguide end-face of a silica-based arrayed waveguide grating (AWG) multiplexer without bulk lenses. To achieve a high optical butt coupling efficiency between the EADFB lasers and the AWG multiplexer, we integrated a laterally tapered spot-size converter (SSC) for the EADFB laser and employed a waveguide with a high refractive index difference of 2.0% for the AWG multiplexer. By optimizing the laterally tapered SSC structure, we achieved a butt-coupling loss of less than 3 dB, which is an improvement of around 2 dB compared with a laser without an SSC structure. We also developed an ultracompact AWG multiplexer, which was 6.7 mm × 3.5 mm in size with an insertion loss of less than 1.9 dB. We achieved this by using a Mach–Zehnder interferometer-synchronized configuration to obtain a low loss and wide flat-top transmission filter spectra. The TOSA body size was 19.9 mm (L) × 6.0 mm (W) × 5.8 mm (H). Error-free operation was demonstrated for a 40-km transmission when all the lanes were driven simultaneously with a low EA modulator driving voltage of 1.5 V at an operating temperature of 55 °C.

A 16-Channel Distributed-Feedback Laser Array with a Monolithic Integrated Arrayed Waveguide Grating Multiplexer for a Wavelength Division Multiplex-Passive Optical Network System Network

A 16-channel distributed-feedback (DFB) laser array with a monolithic integrated arrayed waveguide grating multiplexer for a wavelength division multiplex-passive optical network system is fabricated by using the butt-joint metal organic chemical vapor deposition technology and nanoimpirnt technology. The results show that the threshold current is about 20–30 mA at 25°C. The DFB laser side output power is about 16 mW with a 150 mA injection current. The lasing wavelength is from 1550 nm to 1575 nm covering a more than 25 nm range with 200 GHz channel space. A more than 55 dB sidemode suppression ratio is obtained.

Germanium-on-Silicon Mid-Infrared Arrayed Waveguide Grating Multiplexers

In this letter, we describe the use of a germanium-on-silicon waveguide platform to realize an arrayed waveguide grating (AWG) operating in the 5 μm wavelength range, which can be used as a wavelength multiplexer for mid-infrared (midIR) light engines or as the core element of a midIR spectrometer. Ge-on-Si waveguide losses in the range 2.5-3.5 dB/cm for TE polarized light and 3-4 dB/cm for TM polarized light in the 5.15-5.4 μm wavelength range are reported. A 200 GHz channel spacing 5-channel AWG with an insertion loss/crosstalk of 2.5/3.1 dB and 20/16 dB for TE and TM polarization, respectively, is demonstrated.

Effects of Steam‐Redissolution on Transmission Characteristics of 17 × 17 Polymer Arrayed Waveguide Grating Multiplexers

ABSTRACTIn this article, the RIE process has been improved, a polymer arrayed waveguide grating (AWG) multiplexer with flat spectral response have been designed and fabricated using FPE polymer materials. Using the steam‐redissolution technique, the insertion loss and the crosstalk have been reduced. Experimental results show that the central wavelength is 1550.86 nm, and 3‐dB bandwidth is about 0.478 nm, insertion loss is 10.5 dB, crosstalk is about −20.5 dB. The insertion loss of an AWG device is reduced by about 3 dB for the central channel and 4.5 dB for the edge channels, and the crosstalk is reduced by 1.5 dB after the steam‐redissolution. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2199–2201, 2013

Fabrication of 17×17 box-like spectral response of an arrayed waveguide grating

In the fabrication of a polymeric arrayed waveguide grating (AWG) device, the cores of the channels and the arrayed waveguides exhibit smooth trapezoid cross-sections instead of originally designed rectangular ones after reactive ion etching and steam-redissolution. By employing the Marcatili theory, a method called “equivalent energy flow method” is proposed for analyzing the transmission characteristics of the polymeric AWG with trapezoid core cross-sections. The AWG parameters have been fixed, and a 17×17 polymeric AWG multiplexer has been designed and fabricated. Experimental results show that the central wavelength is 1550.83 nm, and the bandwidth at half maximum is about 0.478 nm; insertion loss is 10 to 13 dB, and crosstalk is about −21 dB .

Comparative investigation and suitability of various data formats for 10 Gb/s optical AWG multiplexer and AWG demultiplexer based transmission links

In this paper, we have analyzed the performance and feasibility for the metropolitan area network based on arrayed waveguide grating (AWG) multiplexers and arrayed waveguide grating (AWG) demultiplexers operating at the bitrate of 10 Gb/s. In the network, the data is successfully transmitted to a distance of 50 km with a very low BER of 1 × 10 −40 thus improving the performance over AWG star based networks. Here, we have observed that arrayed waveguide gratings based multiplexers and demultiplexers for WDM applications prove to be capable of precise multiplexing and demultiplexing of a large number of channels with relatively low losses. This paper also presents the comparative investigation and suitability of various data formats like NRZ Rectangular, NRZ Raised cosine, RZ Rectangular, RZ Raised cosine and RZ super Gaussian for optical transmission link. It has been shown that RZ Raised cosine yields the highest value of Q, good eye opening and lowest BER.

Compact and low insertion loss (~10 dB) Mach-Zehnder interferometer-synchronized arrayed-waveguide grating multiplexer with flat-top frequency response

We have developed a compact Mach-Zehnder interferometer (MZI)-synchronized arrayed-waveguide grating (AWG) multiplexer with 40 100-GHz-spaced channels using 1.5-% Delta waveguides. This MZI-synchronized AWG has a chip size of only 35 x 28 mm(2), and a low insertion loss of 1.0 - 1.2 dB with a flat-top frequency response. This low insertion loss is achieved by i) installing spot-size converters at the ends of optical input and output waveguides, and ii) employing a narrow gap in a directional coupler at the junction of the MZI and AWG. This device exhibited other excellent characteristics including a wide 0.5-dB passband of more than 45 GHz and a low adjacent crosstalk of less than -35 dB.

32-channel arrayed waveguide grating multiplexer using low loss fluorinated polymer operating around 1550 nm

A 32×32 arrayed waveguide grating (AWG) multiplexer operating around the 1550nm wavelength has been designed and fabricated using highly fluorinated polyethers. The propagation loss of the slab waveguide is about 0.3dB/cm at 1550nm wavelength. The channel spacing of the AWG multiplexer is 0.8nm (100GHz). The insertion loss of the multiplexer is 10.3–15.3dB and the crosstalk is less than −20dB.

Narrow-channel-spacing 32-channel AWG multiplexer with an innovative alignment method

A 32-channel 50 GHz spaced arrayed-waveguide grating(AWG) with our innovative configuration has been designed and fabricated. The performance of the device has been fully tested by using a system that consists of a tunable laser light source (TLS), an optical power meter and a polarization controller. The insertion loss (IS) of the device is 4.2–7.4 dB. The crosstalk is about −28 dB. TheIS uniformity is less than 3.3 dB. With our configuration, the performance of the device has been enhanced effectively and the difficulty in alignment process has been decreased obviously.

Fluorinated polymer with high thermal stability for fabrication of 32-channel arrayed waveguide grating multiplexer on silicon

A cross-linkable fluorinated poly (ether ether ketone) (FPEEK) was synthesized for the fabrication of arrayed waveguide grating (AWG) multiplexer. The results of thermal gravimetric analysis (TGA) and near-infrared absorption spectrum show that the materials have high thermal stability and high optical transparency in the infrared communication region. The refractive index of FPEEK can be controlled easily by changing the fluorine content of the materials. The 32-channel AWG multiplexer is fabricated using the FPEEK and oxygen reactive ion etching technology. The AWG multiplexer exhibits that the insertion loss is from 12.8 to 17.8 dB and the channel crosstalk is less than −20 dB. The wavelength channel spacing and the center wavelength are 0.8 nm and 1 548 nm, respectively.

Polymeric 1×32 arrayed waveguide grating multiplexer using cross-linkable fluorinated poly (ether ether ketone) at 1550nm

A 1 × 32 arrayed waveguide grating (AWG) multiplexer operating around 1550 nm has been designed and fabricated using newly synthesized cross-linkable fluorinated poly (ether ether ketone). It has a good processibility and a thermal stability up to 500 °C. The propagation loss of the waveguide is about 0.6 dB/cm at 1550 nm wavelength. The AWG multiplexer has a channel spacing of 0.796 nm and center wavelength of 1548 nm.

Reconfigurable Sampling of the Electric Field at the Reflecting Surface of Folded Arrayed Waveguide Grating Multiplexers

We describe the use of a reflective arrayed waveguide grating multiplexer in conjunction with a digital micromirror device to modulate the electric field distribution in the grating. Modulation of the electric field is accomplished by turning individual digital mirrors on and off. By imposing a reconfigurable grating superstructure on the digital mirror array, we can change the free-spectral range of the device and alter the overall transmission spectra. The experimental results are in excellent agreement with model calculations. This type of a device is expected to be useful in generation of reconfigurable sequences of ultrashort pulses.

Effects of trapezoid core cross-sections on transmission characteristics of polymer arrayed waveguide grating multiplexers

Based on the perturbation theory, a technique named “equivalent rectangular waveguide method” is presented for analyzing the transmission characteristics of arrayed waveguide grating (AWG) multiplexers with trapezoid core cross-sections. As an example, by using this technique, effects of the trapezoid core cross-section on transmission characteristics are performed for a 33×33 polymer AWG multiplexer around the central wavelength of 1.550918 μm with the wavelength spacing of 0.8 nm. Computed results show that the trapezoid core cross-sections result in the shift of the transmission spectrum, and lead to the increase of the crosstalk compared with the device originally designed with exact rectangular core cross-sections. In order to eliminate the shift of the transmission spectrum, decrease the crosstalk, and further realize the accurate demultiplexing, the redesign of the AWG device is carried out.

Mirror Quality and the Performance of Reflective Arrayed-Waveguide Grating Multiplexers

This paper discusses an investigation of the effects of mirror quality on the performance of reflecting arrayed-waveguide-grating multiplexers. Using specially designed external mirrors as external reflectors, the optimum flatness and microroughness of the reflecting surface are determined. The experiments discussed in the paper indicate that a reflecting-surface flatness of /spl lambda//4 is sufficient to obtain high-performance reflective multiplexers. Extrinsic mirror-related phase and intensity errors were found to be negligible for surfaces polished with diamond lapping films with a grain size smaller than 1 /spl mu/m. These experimental results were found to be in excellent agreement with simulations based on mirror-related changes in the waveguide-grating-length increment.

An Efficient Technique for Analyzing Transmission Characteristics of Arrayed Waveguide Grating Multiplexers

An efficient technique is presented for analyzing transmission characteristics of arrayed waveguide grating (AWG) multiplexers. As an example, calculations using this technique are performed for a polymer 33 × 33 AWG multiplexer around the central wavelength of 1.55 μm with the wavelength spacing of 0.8 nm. Computed results show that this technique possesses high accuracy for analyzing the power profile, diffraction efficiency, transmission spectrum, free spectral range and crosstalk of the AWG multiplexer.

Novel structure of an arrayed‐waveguide grating multiplexer with flat spectral response

AbstractA novel structure of arrayed‐waveguide grating (AWG) multiplexers with a graded‐index free‐propagation region (FPR) used to increase the wavelength pass band is presented. The 1‐dB and 3‐dB wavelength pass bands increase with the increase of the graded‐index FPR length. Flat and broadened spectral responses are obtained by using this novel structure. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 444–445, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20165

Improved Design of 8-Channel Silicon-on-Insulator (SOI) Arrayed Waveguide Grating (AWG) Multiplexer Using Tapered Entry into the Slab Waveguides

An improved design of silicon-on-insulator based 8 × 8 AWG multiplexer is presented using tapered entry into the slab waveguide. Our simulation result clearly shows significant enhancement of electric field from 0.44 V/m to 0.732 V/m, reduction in insertion loss from 7.13 db to 2.7 db, with bandwidth of 230 GHz and channel spacing 200 GHz while keeping other parameters within acceptable limits.