Boris Tsap

Recent advances in electrooptic polymer modulators incorporating highly nonlinear chromophore

Based on a nonlinear optical polymer with a highly nonlinear chromophore (CLD) dispersed in an amorphous polycarbonate (APC), we have developed electrooptic (EO) polymer modulators operating at 1550-nm wavelength with low loss and good thermal stability. By incorporating polymer insulation layer, push-pull poling was successfully performed without film damages. We also demonstrated that the propagation loss of the EO polymer waveguide could be reduced as low as 1.2 dB/cm at 1550 nm when the large core waveguide structure was incorporated. The long-term reliabilities of the EO polymer modulator made of CLD/APC polymer were investigated. When the modulator was hermetically sealed in an inert gas, the V/sub /spl pi// change of a Mach-Zehnder modulator was negligible over 30 d of operation with 20-mW exposure to the waveguide input. In the thermal stability measurement, 25% V/sub /spl pi// increase was observed from the sample heated to 60/spl deg/C over 40 d, though the sample left at room temperature showed no decay of nonlinearity.

Polymer electro-optic devices for integrated optics

Abstract Recent advances in polymer electro-optic polymers and in fabrication techniques have made possible advances in polymer optical guided wave devices which bring them much closer to system ready. The processing of a new thermal set FTC polymer and its incorporation into a high-frequency, low-Vπ optical amplitude modulator are reviewed. The design and fabrication of 100 GHz modulators and their integration with rectangular metal waveguides using an anti-podal finline transition with a flexible Mylar substrate is discussed. High-speed polymer modulators with balanced outputs and the in situ trimming of the output coupler is described. More complex guided wave devices using polymers are demonstrated by the photonic rf phase shifter. Techniques for integrating both passive and active polymers into the same optical circuit without the need for mode matching is presented and demonstrated. To reduce the Vπ of a polymer amplitude modulator to 1 V or under, a technique of constant-bias voltage is demonstrated. Finally, a technique to directly laser write electro-optic polymer devices is reviewed.

Electro-optic polymer modulators for 1.55 μm wavelength using phenyltetraene bridged chromophore in polycarbonate

Electro-optic polymer modulators operating at 1550 nm are demonstrated based on a nonlinear optical polymer of a phenyltetraene bridged chromophore in polycarbonate. It has a large electro-optic coefficient (r33=55 pm/V at 1550 nm), good thermal stability (90 °C), and low loss (1.7 dB/cm). A thin protective layer was used in the fabrication of ridge waveguides on the nonlinear polymer. We measured Vπ of 2.4 and 3.7 V at 1300 and 1550 nm, respectively. The chip loss of the modulator at both wavelengths was 5 dB, not including fiber coupling losses.

Demonstration of a photonically controlled RF phase shifter

Integrated photonic radio frequency (RF) phase shifters with dc voltage control have been realized using a nested dual Mach-Zehnder modulator configuration in a new nonlinear optical polymer, CLD2-ISX. These modulators have a V/sub /spl pi// of 10.8 V and exhibit excellent frequency performance measured up to 20 GHz. A near linear phase shift exceeding 108/spl deg/ was obtained for a 16-GHz microwave signal by tuning the dc control voltage over a 7.8-V range. It is expected that these integrated polymer phase shifters will find widespread applications in new types of lightweight optically controlled phased array systems.

High-frequency polymer modulators with integrated finline transitions and low V/sub π/

Ultrahigh-speed integrated electrooptic polymer phase modulators have been fabricated and tested. They are made from a new nonlinear optical polymer, amino phenylene isophorone isoxazolone (APII), and are incorporated with integrated high-speed electrode transitions for W-band (75-110 GHz) operation. This new polymer has also been used to fabricate Mach-Zehnder modulators. These devices show good performance over a wide frequency band ranging to 40 GHz and have a V/spl pi/<10 V. The measurements establish APII, and other chromophores specially designed to minimize chromophore-chromophore interaction, as strong contenders for fabricating modulators for commercial and military applications.

Radiation resistance of electro-optic polymer-based modulators

Mach–Zehnder interferometric electro-optic polymer modulators composed of highly nonlinear phenyltetraene bridge-type chromophores within an amorphous polycarbonate host matrix were investigated for their resistance to gamma rays and 25.6 MeV protons. No device failures were observed and the majority of irradiated modulators exhibited decreases in half-wave voltage and optical insertion losses compared to nonirradiated control samples undergoing aging processes. Irradiated device responses were attributed to scission, cross-linking, and free volume processes. The data suggests that strongly poled devices are less likely to de-pole under the influence of ionizing radiation.

Optically controlled serially fed phased-array transmitter

A new optically controlled phased-array system has been developed that has all the advantages of true time delay (TTD), yet only requires one tunable laser, one optical modulator, and one fiber-optic grating unit. A two-element serial-feed transmitter has been assembled and tested to demonstrate the feasibility of this novel concept. Experimental results include TTD operation from 6-12 GHz using both 10 and 1 ns pulses transmitted to five different directions.

Phased-array optically controlled receiver using a serial feed

Extension of a new optically controlled serially fed phased-array system to the receive mode of operation has been demonstrated. Our system uses the pulsed nature of microwave radars in a manner similar to clocked systems used in digital configurations. This novel approach requires only the use of one tunable laser, one optical modulator, and one chirped fiber grating unit. In this letter, we present an experimental demonstration of a two-element serially fed wide frequency range receiver that validates the feasibility of this novel concept. Our system can. Be readily expanded with multiple elements and transmit/receive modules for a complete phased array system.

High bandwidth polymer modulators

Summary form only given. The measurements of our ultra-fast traveling wave modulators made from electrooptic polymer materials have now been extended to over 110 GHz. A laser heterodyne system using both YAG lasers and tunable semiconductor lasers was used in these measurements which were limited only by the contacts to the device.

High speed polymer electro-optic modulators

We have used this polymer technology to fabricate modulators with balanced outputs by including a 3 dB coupler on the output and incorporated them in a digital time delay array. Arrays of RF photonic phase shifter operating at 20 GHz has also been demonstrated. For more complex integrated optical circuits, it will be important to use low loss passive polymers to interconnect the active polymer devices.