Starting with a waveguide amplifier as a crucial building block among many others, we demonstrate a library of optical elements that can be seamlessly integrated on a single silica-on-silicon chip and produce complex integrated optical circuits. This new level of planar waveguide integration is made possible by recent advances in our waveguide manufacturing technology capable of combining up to three different core materials on the same wafer. We discuss in details the performance and applications of these elements as well as new circuits, such as an amplified reconfigurable add-drop module.
From its foundation Inplane Photonics focused on developing integrated solutions based on Planar Lightwave Circuit(PLC) technology. It is universally agreed that the path to lower cost-per-function in Photonics, as in Electronics, leads to integration. The timing of introduction of a new technological solution and the rate at which it will penetrate the market very much depends on the interplay between the size of the market, advantages the new technology offers, and the investment needed to achieve the level of performance that is envisioned. In telecom applications, where the main drivers for technology selection are cost and performance, such large-scale investment did not materialized yet for the PLC technology mostly due to a limited market size.
Planar waveguide technology has long been touted as the major platform for optical integration, which could dramatically lower component/module size and cost in optical networks. This technology has finally come to maturity with such waveguide-based optical products as wavelength multiplexers, switches, splitters and couplers, which are common nowadays. However, its potential as a complete solution for integration of a subsystem on a chip has so far been limited by the lack of integrated active elements providing gain to deteriorating optical signals. As the signal propagates through the fiber-optic network, it dissipates its energy and requires amplification in the network subsystems to maintain a required signal to noise ratio. Discrete fiber amplifiers are designed into systems and maintain required signal levels. However, if new components are introduced or the current ones are changed, current amplifiers have a limited ability to compensate for changes. Inplane's solution to the signal degradation problem is an optical amplifier that can be integrated onto the same planar waveguide platform as the other passive elements of the subsystem. Subsystems on such a platform will be able to automatically and internally adjust signal optical power, and enable simple interfacing between optical modules, module replacement and upgrades in the network. Inplane Photonics has developed Er-doped waveguide amplifier (EDWA) technology, which is fully compatible with the glass-on-silicon waveguide platform. In this paper we will present recent EDWA performance that approaches that of a fiber amplifier. Furthermore, we will demonstrate several examples of practical integration between passive and active building blocks on a single optical chip.
One of the trends that persist in the telecom industry in all market conditions is a continuous push towards lower cost and higher performance optical components. Unlike today’s networks, a more cost efficient network of tomorrow will contain many components utilizing Planar Lightwave Circuits (PLC) technology. PLC technology is a platform for optical integration that could dramatically lower cost-per-function in many optical networks. However, integration may result in degraded optical performance due to higher insertion losses as compared to “standard” fiber-based solutions. A solution to the loss problems is an optical amplifier that can be integrated on the same PLC platform and used to restore optical signals as needed. Inplane Photonics is developing Er-doped waveguide amplifier (EDWA) technology, which is fully compatible with a glass-on silicon PLC platform. We identify that an EDWA is a necessary building block to achieve the full potential of optical integration. In this paper we will present recent EDWA performance that approaches that of an EDFA. Furthermore, we will demonstrate several examples of practical integration between passive and active building blocks on a single PLC chip.
Recent studies of lasing and stimulated emission in luminescent (pi) -conjugated polymers performed by our group are presented. Optical properties of cylindrical, high-Q, polymer microcavities are discussed. The emission spectra of plastic microring and microdisk lasers were measured and analyzed. Cylindrical light emitting polymer microdiodes, as possible candidates for electrically-driven plastic lasers have been fabricated. Stimulated emission and lasing were also demonstrated for polymer solutions infiltrated in opal photonic crystals. In addition, two unusual regimes of stimulated emission characterized by narrow laser-like spectral lines were found in thin waveguiding polymer films. These regimes may be associated with random optical feedback introduced by light scattering inside the polymer films and amplified Raman scattering, respectively.
We demonstrate the use of a color center laser in a pump- and-probe correlation technique which enables us to extend the probe spectral range into the infrared. As a result, we find strong photoinduced infrared absorption in several (pi) -conjugated polymers and oligomers. We associate this absorption with optical transitions in the singlet exciton manifold.
We have investigated the lasing properties of several luminescent conducting polymers, i.e. DOO-PPV and the bi- substituted polyacetylenes PDPA-nBu, and PH<SUB>x</SUB>PA, dissolved in various polar and non-polar solvents. PPV polymers emit with high quantum efficiencies in broad emission bands cantered in the orange/red region of the spectrum, depending on the solvent, and the PDPA polymers emit in the blue/green region. Our tested laser resonators include polymer solutions excited with 100 ps pulses from a regeneratively amplified mode-locked Nd:YAG laser. We obtain pulsed, low-threshold laser operation with repetition rate of up to 1 kHz. Resulting mainly from recent reported originally in the literature. The dependencies of threshold pump energy and output versus input power characteristics on material parameters are investigated for a fixed optical gain length. The results are compared with the standard Rhodamine 590 organic dye system used in the same wavelength regions. We have observed that the well know phenomenon of 'concentration quenching' in dye molecules does not happen in polymers. Spectral narrowing in PDPA-nBu solution, emitting near 500 nm, is also obtained for the first time.
We discuss both cooperative radiation and stimulated emission and consider their role in spectral narrowing of luminescent conducting polymers. We argue that cooperative radiation is favored in films with poor optical confinement. On the other hand, directional stimulated emission can be observed in dilute solution and thin films with superior optical confinement. Spectral narrowing in this case can be achieved by increasing either the excitation length or excitation intensity. The optical gain and loss coefficients are measured. Narrow line (approximately 1.5 cm<SUP>-1</SUP>) laser emission is observed in cylindrical microcavities formed by thin polymer films coated around glass fibers in the red and green spectral ranges. The cavity quality factors of these plastic lasers are mainly determined by selfabsorption and estimated to be about 5000.
We have employed the time-resolved photomodulation (PM) technique to study the photoexcitation dynamics of a luminescent (Si-PT) and nonluminescent (s-(CH)<SUB>x</SUB>) conducting polymers in the low signal limit. In each polymer, we identify two exponential decay processes in the PM decay, with characteristic time constants T<SUB>1</SUB> and T<SUB>2</SUB>, where T<SUB>1</SUB> is of order 1 ps and T<SUB>2</SUB> depends on the specific polymer; T<SUB>2</SUB> in Si-PT is about 50 ps, whereas T<SUB>2</SUB> in s-(CH)<SUB>x</SUB> is about 5 ps. The difference in T<SUB>2</SUB> is tentatively attributed to radiative and non-radiative recombination kinetics, respectively. We also found that the PM decay does not show any obvious temperature and intensity dependences, whereas the polarization memory decay is longer at low temperatures.