Chirp-Compensated DBR Lasers for TWDM-PON Applications

Abstract

We propose a novel chirp compensation scheme for directly modulated threesection distributed Bragg reflector (3s-DBR) lasers in applications of the time-and wavelength-division multiplexed passive optical network systems. The frequency chirp of 3s-DBR lasers induced by direct modulation is investigated through extensive numerical simulations based on the time-domain travel-wave model. To overcome the signal distortions resulting from the frequency chirp due to direct modulation, we extend on our novel idea of frequency chirp compensation technology with inherent characteristics of DBR-type tunable lasers. Q factors and extinction ratio for different system transmission lengths are analyzed and compared. Large dispersion tolerance of the system is achieved by using the chirp compensation scheme.

A Chirp-Managed Tunable DBR Laser Based on Novel Cascaded Gratings

“…The output end-face of the laser is the cleavage plane and the end-face of the grating section is anti-reflection coated with zero reflection. By substituting equations (9)-(12) to the equations (2), (3) and (8), the optical field F and R can be solved, and the static characteristics, including lasing wavelength and optical spectrum, can be obtained by fast Fourier transform of the optical field.…”

“…Another important issue for the directly modulated DBR lasers applied in TWDM/WDM systems is the frequency chirp, which will result in spectrum broaden that severely limits the maximum achievable system transmission capacity due to the fiber dispersion. In our previous work, we proposed a chirp compensated scheme to reduce DBR laser chirp by injecting reverse modulation current into phase section [8]. This method mainly reduces the adiabatic chirp and could extend the transmission distance to 150 km at 2.5 Gb/s, however it would be ineffective when the bitrate is increased up to 10 Gb/s since the transient chirp is dominant at higher modulation speed.…”

“…This method mainly reduces the adiabatic chirp and could extend the transmission distance to 150 km at 2.5 Gb/s, however it would be ineffective when the bitrate is increased up to 10 Gb/s since the transient chirp is dominant at higher modulation speed. Chirp-managed laser (CML) has been demonstrated as a competitive solution to provide high dispersion tolerance for metro/access systems [8], in which a directly modulated laser is followed by an optical spectrum reshaping (OSR) filter. Different directly modulated lasers are used as sources, such as DFB laser [9], tunable modulated-grating Y-branch (MG-Y) lasers [10], DFB laser array [11] and DBR laser [12].…”

Generation of mid-infrared supercontinuum by designing circular photonic crystal fiber

“…In recent years, photonic crystal fibers (PCFs) made of the silica glass have played an important role in supercontinuum (SC) generation due to the availability of suitable pump sources and the design flexibility of dispersion. [1][2][3] Remarkably, silica suffers from severe infrared absorption at wavelengths beyond 2.2 µm, which makes it impossible to extend the generated SC far into the mid-infrared (MIR) region. [4] However, MIR-SC generation is an emerging research field driven by a large number of potential applications, such as spectroscopy, microscopy, frequency metrology, and remote sensing.…”

Identifying the Contribution of Carrier Shot Noise and Random Carrier Recombination to Excess Frequency Noise in Tunable Lasers

“…Tunable lasers are vital components within every transponder of modern coherent optical communications systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].To date, narrow linewidth tunable lasers, with linewidths~100 kHz based on thermally tuned external cavity lasers, are the tunable laser technology that dominates the market for systems with line rates of 100 Gbit/s, 400 Gbit/s and beyond [7]. The reliance on thermal tuning makes these lasers unsuitable for sub-microsecond wavelength tuning times, as demanded by state-of-the-art transponders for the next-generation passive optical networks (NG-PON2) [2,8]. While NG-PON2 standards aim to deliver line rates of 10 Gbit/s per user, per wavelength, given the rapid rise in data consumption by users and the internet of things, data communication rates will need to increase in excess of 10 Gbit/s per user, with ultra-fast wavelength tuning of the laser transmitters to unused channel slots to maximise the available transmission capacity.…”