Slotted Fabry-Perot Laser Research Articles

Stable injection locking with slotted Fabry–Perot lasers at 2 μm

Injection locking has many applications in telecommunications systems, such as narrowing linewidths, increasing bandwidth and improving filtering. Beyond telecommunications, injection locking is widely used in remote sensing. This is of particular interest for applications in the 2 μm region, where gases such as carbon dioxide, water vapour and methane have identifiable absorption features. In this paper, we demonstrate stable injection locking with slotted Fabry–Perot lasers in the 2 μm wavelength region. Injection locking was observed in both the optical domain and power spectrum; with key features recorded such as injection ‘pulling’, side-mode suppression and the characteristic quiet region in the electrical domain denoting single-frequency emission and stable locking. The effect of varying the injection ratio was investigated, with a decreased injection ratio corresponding to a reduction in the locking bandwidth. Finally, the lasers were shown to remain injection locked, with no thermal drift, for over 24 h, indicating their suitability for implementation in a real-world telecommunications system.

Monolithically integrated low linewidth comb source using gain switched slotted Fabry-Perot lasers.

A monolithically integrated low linewidth optical comb is demonstrated by gain switching of a three-section laser device. The device consists of a slave and master section separated by a shared slotted mirror section. Wavelength tunability has been demonstrated by varying the electrical bias of each section. The number of comb lines is shown to almost double with the addition of optical injection from the master section into the slave. The unmodulated device has a full width half max linewidth of ∼ 500 kHz, while the comb line set were measured to be ∼ 600 kHz, with little degradation as a result of gain switching. The FSR (free spectral range) of the demonstrated comb is 4 GHz, which is tunable within the bandwidth of the device, with a central wavelength of 1580.3 nm.

Theoretical Analysis of Tunable Three-Section Slotted Fabry–Perot Lasers Based on Time-Domain Traveling-Wave Model

In this paper, we present a simple time-domain traveling-wave dynamic model for the simulation of wavelength tunable three-section slotted Fabry-Perot (3s-SFP) semiconductor lasers. The longitudinal spatial hole burning, the nonlinear gain compression, and the refractive index changes with carrier density are included in this model. The slot structure is characterized by using the boundary conditions of the optical fields propagating through the slot facets. For the first time, the tuning mechanism of the 3s-SFP laser is studied in detail by using the proposed model. Characteristics of the 3s-SFP laser including the lasing wavelength, the side-mode suppression ratio, the output spectrum, and the wavelength switching dynamics are simulated. The potential of increasing the tuning range of the 3s-SFP laser is also discussed by optimizing design parameters of the device. Virtual digital infinite-impulse response bandpass filters with different central wavelengths are developed to examine the mode power of different channels during wavelength switching events. Switching times of approximately 2-5 ns are demonstrated theoretically. Good agreements have been found between the simulation results and the experimental measurements.

On-chip optical phase locking of single growth monolithically integrated slotted fabry perot lasers

This work investigates the optical phase locking performance of Slotted Fabry Perot (SFP) lasers and develops an integrated variable phase locked system on chip for the first time to our knowledge using these lasers. Stable phase locking is demonstrated between two SFP lasers coupled on chip via a variable gain waveguide section. The two lasers are biased differently, one just above the threshold current of the device with the other at three times this value. The coupling between the lasers can be controlled using the variable gain section which can act as a variable optical attenuator or amplifier depending on bias. Using this, the width of the stable phase locking region on chip is shown to be variable.

Single-mode and wavelength tunable lasers based on deep-submicron slots fabricated by standard UV-lithography

By reversing the pillars formed on SiO2 mask sidewalls, it is possible to fabricate deep-submicron slots with width down to 240nm by standard UV-lithography. Based on this newly developed process, a single-mode slotted Fabry-Perot laser and a wavelength tunable laser with periodically distributed slots are designed, fabricated and characterized. Numerical analysis shows the low-loss advantage of deep-submicron slots. Experimentally, the slotted Fabry-Perot laser showed a low threshold current of 22mA and the tunable slotted grating laser exhibited a maximum side mode suppression ratio (SMSR) of 43dB and a discretely tuning range of about 38nm. The method has excellent potential for low cost fabrication of photonic devices with deep-submicron features without using expensive tools such as the e-beam lithography.

Improved spectral characteristics of 980 nm broad area slotted Fabry—Perot diode lasers

A novel broad area slotted Fabry—Perot diode laser is designed and fabricated. Using a new semi-analytical method, we introduce effective refractive index perturbations in the form of etched slot features into a conventional 980 nm broad area Fabry—Perot cavity, and the spectral characteristics of the device are expected to be noticeably improved. A low density of slot features is formed by using standard optical lithography and inductively coupled plasma dry etching. The experimental results show that the full spectral width at half-maximum is less than 0.4 nm, meanwhile, the thermal shift of the emission spectrum is decreased from 0.26 to 0.07 nm/°C over a temperature range of 10 to 60 °C. The improved spectral characteristics of the device are proved to be attributed to such slotted Fabry—Perot laser structures.

Fast Switching Slotted Fabry–Perot Laser for Phase Modulated Transmission Systems

In this paper we characterize the switching dynamics of a novel three section slotted Fabry-Perot laser for phase modulated transmission systems. The static characterization shows that an average linewidth of 538 kHz is achieved for all 25 ITU 100 G channels of the laser, which is able to support differential quadrature phase-shift-keying (DQPSK) transmission at 10 Gbd symbol rate. An average wavelength switching time of 5 ns is also demonstrated using two measurement techniques. The performance during switching is examined by measuring the time resolved bit error rate (BER) of a 10.7 Gbd DQPSK packet transmission system. The time taken to go from no measured errors on one channel to no measured errors on the other channel is found to be less than 16 ns for the switching combination studied.

Characterization of a tunable three-section slotted Fabry–Perot laser for advanced modulation format optical transmission

In this paper we report on the characterization of a narrow linewidth three-section tunable slotted Fabry–Perot laser. The SMSR of the 25 available 100-GHz ITU channels is above 30 dB, whereas their average linewidth is 538 kHz with a maximum below 800 kHz. The RIN spectra of six different channels are also measured and a maximum average RIN of −135 dB/Hz is obtained. The linewidth effect of the laser in a 1.25 Gb/s DPSK transmission system is investigated by comparing the performance between the slotted Fabry–Perot laser and a commercial SG-DBR laser respectively. Error free transmission of the slotted Fabry-Perot laser shows the benefit of the narrow linewidth of the device for systems employing advanced modulation formats.

Fast Wavelength Switching Lasers Using Two-Section Slotted Fabry–PÉrot Structures

Fast wavelength switching of a two-section slotted Fabry-Perot laser structure is presented. The slot design enables operation at five discrete wavelength channels spaced by 10 nm by tuning one section of the device. These wavelengths operate with sidemode suppression ratio in excess of 35 dB, and switching times between these channels of approximately 1 ns are demonstrated