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

Abstract

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.

Off-Axis Cavity-Enhanced Absorption Spectroscopy of 14NH3 in Air Using a Gain-Switched Frequency Comb at 1.514 μm

“…Hence, GSFCs are suited for monitoring of NH 3 in industrial environments when used in conjunction with a robust off-axis cavity approach. Future work will focus on significantly more compact custom-designed photonically integrated combs (with even smaller FSR) [16,50] and on improving the detection resolution and speed through a dual comb approach [10]. Detection sensitivities at low ppbv levels are expected by employing higher finesse optical cavities.…”

“…The technique enables tunability of the frequency comb’s center wavelength and of the free spectral range, also making it a suitable light source for trace gas detection. GSFCs are generally inexpensive in comparison to mode-locked femtosecond FCs, and they can be miniaturized through monolithically integrated device designs [13,14,15,16]. In 2016, GSFC-based dual-comb architecture was reported in an absorption study of H 13 CN in the 1.5 µm region [17].…”

Mode Suppression in Injection Locked Multi-Mode and Single-Mode Lasers for Optical Demultiplexing

“…Here, γ g and γ c are the rates of cavity gain and cavity losses, f d is the longitudinal mode spacing, α H is the linewidth enhancement factor, and ∆ω = ω 1 − ω 0 is the difference between the natural frequencies of the master and slave laser. In the steady state, Equation (9) gives us a relation between the growth and decay rates inside the laser:…”

“…The power consumption and cost of coherent comb sources can be further reduced through photonic integration. Designs using monolithically-integrable injection locked gain switched lasers have previously demonstrated coherent combs on InP, with optical spacings between 4 GHz and 10 GHz [9,10]. The use of these optical combs however requires each comb line to be demultiplexed, in order to enable each frequency to be individually modulated with data.…”

A Comparison between off and On-Chip Injection Locking in a Photonic Integrated Circuit

“…The epitaxial structure used was commercially grown 1550 nm laser material on an InP substrate, with a total active region thickness of 0.4 µm, consisting of five compressively strained AlInGaAs quantum wells. The device was fabricated using standard processing techniques, similar to [13][14][15]. The SFPs were controlled by independently biasing their respective mirror, I Mirror , and gain, I Gain , sections.…”