An experiment was performed using two-channel wavelength division multiplexing and demultiplexing devices to determine the feasibility of using 1260 nm and 1330 nm lasers. The experiment showed that it was feasible to use wavelengths with separation of 70 nm; however, these devices would not be standard commercial devices. The devices were manufactured using dichroic coatings designed for two specific wavelengths. Pigtails were mounted on the devices so that connectors could be used to couple into a 10 km span of fiber. The results of the experiment show the insertion loss of the devices, crosstalk from Channel 1 to Channel 2, and a comparison of bit error rate performance.
Results on the development of an experimental four channel fiber optics Wavelength Division Multiplexing (WDM) system with 10 nanometer channel spacing will be presented. Data on WDM demultiplexers utilizing narrow band interference filters will be reviewed. Results on studies of wavelength stability of semiconductor lasers for WDM will also be presented.
Wavelength division multiplexing has been shown in recent years to be a viable approach to increasing the transmission capacity of fiber-optic communication links. The advantage offered by a dispersive component over some of the other WDM methods is a high channel capacity which avoids all cummulative losses. The use of a quarter pitch graded index rod results in a fully integrated device which is both compact and rugged, having no exposed optical interfaces which can become damaged. This paper concentrates on the GRINrod-prism grating approach with emphasis on test methods and on design parameters, as well as, fabrication techniques. The following topics related to these items will be discussed:
A codirectional two-channel wavelength division multiplexing subsystem using lensed dichroic multiplex and demultiplex couplers was designed, fabricated, and tested for use in an analog data link. Nominal channel central wavelengths of 780 nm and 880 nm were selected to match' the emission peaks of high-performance injection laser diodes. A short-wavelength-pass dichroic filter which progressed from >90% transmission at 810 nm wave-length to >90% reflection of 830 nm provided the wavelength selectivity of the couplers. The subsystem was tested with 900 m of 50 μm/125 μm core/cladding diameter graded-index optical fiber linking the couplers and with 790 nm and 860 nm laser diode sources. Over the range 0°C to +50°C, total coupler optical power losses in the short and long wavelength channels averaged 2.4 dB and 3.8 dB, respectively. Over the same temperature range, cross-talk rejection was 33 dB in the 780 nm channel and 50 dB in the 880 nm channel. Measured overall optical performance agreed well with projected performance calculated from individual component characteristics. The subsystem passed mechanical shock tests and vibration tests per MIL-T-1522F(AS).
Present DS-3 optical interfaces convert the Bell compatible bipolar signal from a multiplexer to a scrambled NRZ format prior to driving the laser transmitter. Bipolar optical transmission is now a reasonable alternative to scrambled NRZ transmission due to improved sources which possess increased linearity, lower thresholds, and better temperature stability. This paper discribes the advantages, disadvantages, and system considerations of a bipolar optical interface.
A long-wavelength bidirectional Wavelength Division Multiplexed (WDM) fiber-optic system was recently designed and developed as part of an Exploratory Development Program for the U. S. Army Communications/Electronics Command at Fort Monmouth, N.J. Test results are summarized and discussed herein and possible system variants are explored.
Three methods have been used successfully in fabricating evanescent optical couplers with single mode and multimode optical fibers. These approaches comprise cementing fibers into plates before grinding and polishing, embedding the fibers in lower melting temperature glass before grinding and polishing, and stretching adjacent fibers while heating them. Comparisons are made among the couplers produced by the three methods with regard to stability of the coupling ratio with ageing, changes in temperature and changes in light polarization.
A polygonal structure optical multi/demultiplexer with optimum interference filter arrangement is proposed. In the experiment, a 5-channel multi/demultiplexer was fabricated with low insertion loss, below 1 dB, and high stability against temperature change was attained.
A fiber optic transceiver and network compatible with all Ethernet local area network hardware and software are presented. The description, theory of operation, and feasibility analysis of a 1024 node system are given. Several installations of fiber optic Ethernet systems are described.
Exploiting Gbit/s photonic circuits and optical interconnect schemes for chip-to-chip communication promises to facilitate the development of large, highly parallel network computers that can solve computationally intensive tasks. The basic concept, potential applications, and key technological issues required to implement this approach are presented in this paper.
A fiber optic multiplexer and demultiplexer system is described. The Wavelength Division Multiplexing system produces its own spectral sources through a "slicing" of the wide spectral bandwidth of LED sources into individual narrow bandwidth data channels. This technique provides an inexpensive method of creating several WDM channels from a single type of low cost LED. The multiplexer/demultiplexer system uses holographic aberration reduced concave diffraction gratings as the sole optical components.
Optical interference filters have operational characteristics which make them particularly suited for multiple wavelength unidirectional and bidirectional communications systems. In order to achieve desired channel wavelength separation of 30nm with less than 35dB crosstalk, proposed multiplexing schemes require filters which have steep cuton and/ or cutoff slopes and high in-band transmittance. These requirements have provided the impetus for OCLI to advance the state-of-the-art in filter design.