Multi-wavelength Transmitter Research Articles

Four-channel CWDM device on a thin-film lithium niobate platform using an angled multimode interferometer structure

A compact and high-performance coarse wavelength-division multiplexing (CWDM) device is introduced with a footprint of 2.1 mm × 0.02 mm using an angled multimode interferometer structure based on a thin-film lithium niobate (TFLN) platform. The demonstrated device built on a 400 nm thick x -cut TFLN shows ultra-low insertion losses of < 0.72 dB . Measured 3 dB bandwidths are 12.1 nm for all channels, and cross talks from adjacent channels are better than 18 dB. Its peak wavelength positions comply with the CWDM standard with a channel spacing of 20 nm. The filter bandwidth of the proposed CWDM device can be tuned by adjusting the structural parameters. This demonstrated CWDM device will promote future realization of multi-channel and multi-wavelength transmitter chips on TFLN.

Non-Standalone 5G NR FiWi System Based on a Photonic Integrated Multi-Wavelength Transmitter

This letter presents a non-standalone 5G new radio (NR) multiband fiber-wireless (FiWi) system implemented using an integrated multi-wavelength transmitter with direct modulation. In this system, three 4G/5G RF signals are simultaneously transported over a 12.5-km long radio over fiber (RoF) link, before being amplified and radiated: a 20-MHz 5G NR signal at 788 MHz; five 20-MHz LTE subcarriers at 2.6 GHz; a 100-MHz 5G NR signal at 3.5 GHz. Wireless transmissions through a 10-m long indoor picocell-like link and a 115-m long realistic outdoor wireless link are demonstrated. All 4G and 5G received signals comply with the 3GPP Release 15 requirements, in terms of EVM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RMS</sub> , except for 16 QAM at 3.5 GHz on the 115-m link. Experimental results demonstrate a total throughput of 1.36 Gbit/s and 230 Mbit/s on the 10-m and 115-m scenarios, respectively.

5G NR RoF System Based on a Monolithically Integrated Multi-Wavelength Transmitter

We propose and demonstrate the use of a monolithically integrated multi-wavelength transmitter for multiband 5G new radio (NR) radio-over-fiber (RoF) systems, simultaneously operating in the standalone (SA) and non-standalone (NSA) modes. The novel integrated photonic circuit, integrating eight tunable and directly modulated distributed feedback lasers, aims to reduce the transmitter complexity and footprint, enabling compact, high-performance and low-cost 5G solutions for frequencies up to 10 GHz. We report the implementation of a 4G/5G shared optical mobile fronthaul using two 5G NR and a LTE-A signals, evaluated in two distinct scenarios, as a function of root mean square error vector magnitude (EVMRMS) and in accordance to the 3GPP Release 15 requirements. In the first phase, three optical carriers in C-band are independently modulated with three mentioned RF signals, whereas subcarrier multiplexing (SCM) is applied to the second scenario for jointly modulating an optical carrier at 1554 nm. Gbit/s throughput is demonstrated for validating the applicability of our monolithically integrated multi-wavelength transmitter either for enabling multiapplication and/or diverse RF standards, using a single wavelength or multiservice exploiting different wavelengths from an unique optical source.

InP Monolithically Integrated Transmitters Based on High Speed Directly Modulated DFB Lasers

In this paper we summarize results concerning high-speed integrated multi-wavelength transmitters fabricated using a generic InP integration platform. The photonic integrated circuits (PICs) include tunable directly modulated DFB lasers emitting in the C-band, monitoring photodetectors, MMI couplers and output spot size converters. The directly modulated lasers, designed in order to fit within a 100 GHz grid, show a maximum 3-dB small signal bandwidth of 21 GHz and a tunability range of about 4 nm. In particular, we report an 8-channel transmitter showing operation up to 30 Gb/s per channel (for 200+ Gb/s applications) and a 4-channel transmitter capable of operating up to 34 Gb/s per channel (for 100+ Gb/s applications). Error free operation (bit error rates <10−9) is achieved for all the channels in all the cases.

A Directly Modulated Multiwavelength Transmitter Monolithically Integrated on InP

This paper presents an integrated multiwavelength transmitter with eight channels realized on a generic InP integration platform. The photonic integrated circuit (PIC) comprises eight tunable directly modulated distributed feedback lasers emitting in the C-band, eight monitoring photodetectors, and MMI couplers. The PIC has been mounted on a printed circuit board for easier operation and wavelength control. The directly modulated lasers, designed with a 100 GHz spacing between 1541.4 and 1547 nm, show a 3-dB bandwidth up to 12 GHz and a tunability range of about 4 nm. Transmission experiments demonstrate error-free operation in back-to-back and open eye-diagrams up to 20 Gb/s per channel, while short-range communications (along a 2.1 km fiber span) up to 15 Gb/s per channel incur in a limited power penalty (4.5 dB at a bit error rate = 10 −9).

Optical links for detector instrumentation: on-detector multi-wavelength silicon photonic transmitters

We report on our recent progress in developing an optical transmission system based on wavelength division multiplexing (WDM) to enhance the read-out data rate of future particle detectors. The design and experimental results of the prototype of a monolithically integrated multi-wavelength transmitter are presented as well as temperature studies of electro-optic modulators. Furthermore, we show the successful permanent coupling of optical fibers to photonic chips, which is an essential step towards packaging of the opto-electronic components.

Integrated multi-wavelength transmitters for parallelism in single-mode, high-speed optics

Integrated multi-wavelength transmitters for parallelism in single-mode, high-speed optics

AWG-Based Photonic Transmitter With DBR Mirrors and Mach–Zehnder Modulators

In this letter, we demonstrate a novel monolithically integrated photonic multiwavelength transmitter that was realized by integrating an arrayed waveguide grating-based laser with selective distributed Bragg reflector mirrors and Mach-Zehnder modulators. The integrated circuit was designed according to a generic integration model, by utilizing standardized photonic building blocks, and was fabricated on an InP-based platform in a multiproject wafer run. The device delivers above 1 mW of optical power into the fiber with a side mode suppression ratio better than 40 dB. The linewidth of the generated signals is 275 kHz. We achieved error free 50-km transmission at the modulation data rate of 10 Gb/s per channel, for a received power of -26.5 dBm.

InP-Based Photonic Multiwavelength Transmitter With DBR Laser Array

We demonstrate an InP-based photonic multiwavelength transmitter realized by integrating an array of distributed Bragg reflector lasers with modulators in Mach-Zehnder configuration. An arrayed waveguide grating is used to multiplex the generated signals into a common optical output. The device is designed according to a generic integration concept, using standardized building blocks, and is fabricated in a multiproject wafer run. The device delivers up to 4 dBm of optical power into the fiber with a modulation data rate of 12.5 Gbps per transmission channel. The obtained performance makes it very promising for application in the next generation optical access networks as a key source in the central office part of the telecommunication systems.

High Efficiency Automatic-Power-Controlled and Gain-Clamped EDFA for Broadband Passive Optical Networking Systems

The configuration of a simple improved high efficiency automatic-power-controlled and gain-clamped EDFA (APC-GC-EDFA) for broadband passive optical networking systems (BPON) is presented here. In order to compensate the phase and amplitude variation due to the different distance between the optical line terminal (OLT) and optical network units (ONU), the APC-GC-EDFA need to be employed. A single 980 nm laser module is employed as the primary pump. To extend the bandwidth, all C-band ASE is recycled as the secondary pump to enhance the gain efficiency. An electrical feedback circuit is used as a multi-wavelength channel transmitter monitor for the automatic power control to improve the gain-flattened flatness for stable amplification. The experimental results prove that the EDFA system can provide flatter clamped gain in both C-band and L-band configurations. The gain flatness wavelength ranging from 1530 to 1610 nm is within 32.83 ± 0.64 dB, i.e. below 1.95 %. The gains are clamped at 33.85 ± 0.65 dB for the input signal power of −40 dBm to −10 dBm. The range of noise figure is between 6.37 and 6.56, which is slightly lower compared to that of unclamped amplifiers. This will be very useful for measuring the gain flatness of APC-GC-EDFA. Finally, we have also demonstrated the records of the overall simultaneous dynamics measurements for the new system stabilization. The carrier to noise ratio (CNR) is 49.5 to 50.8 dBc which is above the National Television System Committee (NTSC) standard of 43 dBc, and both composite second order (CSO) 69.2 to 71.5 dBc and composite triple beat (CTB) of 69.8 to 72.2 dBc are above 53 dBc. The recorded corresponding rise-time of 1.087 ms indicates that the system does not exhibit any overshoot of gain or ASE variation due to the signal at the beginning of the pulse.

Multi-wavelength optical transmitter based on time-domain modulation of directly modulated wavelength-swept light

A multi-wavelength optical transmitter that employs time-domain modulation of directly modulated wavelength-swept light is proposed. This scheme offers the simplicity and flexibility needed for future optical access networks based on high spectral density wavelength division multiplexing. A proof-of-concept demonstration of the generation and selective detection of four-channel 1.25 Gbit/s signals is shown.

Low-noise multiwavelength transmitter using spectrum-sliced supercontinuum generated from a normal group-velocity dispersion fiber

Aiming at the application of supercontinuum (SC) generated from a fiber with a normal group-velocity dispersion (GVD) to multiwavelength transmitters, we theoretically study the enhancement of optical-amplifier noise in the SC-generation and spectrum-slicing processes. We find that significant enhancement of noise is not observed in these processes. The bit error rate measurement actually shows that the power penalty induced by these processes is less than 1 dB in all spectrum-sliced channels. These results assure low noise of the multiwavelength transmitter using spectrum-sliced SC generated in a normal GVD fiber.

Multifrequency lasers and applications in WDM networks

The current status and applications of multifrequency lasers (MFL) are reviewed. An MFL consists of an array of N optical amplifiers monolithically integrated with a 1/spl times/N optical multiplexer. The laser provides the functionality of N independent lasers whose optical wavelengths are precisely locked together by the common intracavity optical multiplexer. The design of an MFL together with its fundamental characteristics are discussed, and state-of-the-art results are shown. The functionality of an MFL is compared to that of an integrated DFB array. Finally, we show some applications of single-wavelength tunable transmitters and multiwavelength transmitters.