Broad wavelength coverage 23  μm III-V-on-silicon DFB laser array

Abstract

Silicon photonics is a promising integrated-optics platform for optical communication and sensing applications. Integrating 2-3 μm wavelength widely tunable lasers on silicon photonic integrated circuits enables fully integrated spectroscopic sensors with different potential applications such as multi-species trace gas spectroscopy and bio-molecule detection. Here, we demonstrate a continuous-wave (CW) operated III-V-on-silicon distributed feedback (DFB) laser array covered a broad wavelength range from 2.28 to 2.43 μm. CW operation up to 25°C and an on-chip output power of 2.7 mW in a single mode at 5°C is achieved for lasers operating at 2.35 μm wavelength. Four-channel DFB laser arrays with a continuous tuning range of 10 nm and side mode suppression ratio of 40 dB over the whole range are also presented. This work is a major advance toward chip-scale silicon photonics spectroscopic sensing systems. Gas sensing based on short-wave infrared and mid-infrared absorption spectroscopy has been proven to be a reliable technology for trace-gas measurements with fast response time and a high degree of specificity to the target gas [1,2]. However, most present optical sensors consist of discrete optical components and a bulk gas cell, which limits their viability for applications in portable and economical gas analysis. Integrated photonics platforms offer the potential to realize miniature and low-cost optical gas sensors [3][4][5][6]. As one of the most promising integrated photonics platforms, silicon photonics has been well-developed for optical communication applications during the past decade [7]. In recent years, its applications have been extended to sensing applications, including on-chip spectroscopic sensing [8]. Silicon photonics gas sensors that target different components have been demonstrated, including those that use, e.g., microring resonators [9,10] or spiral waveguides [11] to interact with the gas medium. In these gas sensors, the light from an external laser source is coupled into the silicon chip for the on-chip absorption spectroscopy measurement. The development of fully integrated silicon photonic integrated circuits (PICs) in the 2.3 μm wavelength range enable compact gas sensors with high sensitivity, since many important industrial gases (e.g., NH 3 , CO, and CH 4 ) have strong absorption lines in this wavelength range [12]. It is also valuable for bio-sensing applications, such as non-invasive blood glucose measurements [8,13]. For a compact silicon photonics spectroscopic gas sensor, an integrated and tunable single-mode laser is the key component that should be developed. Recently, heterogeneously integrated III-V-on-silicon Fabry-Perot lasers around 2 μm were realized using strained InGaAs Type I heterostructures [14]. However, the emission wavelength range of laser sources based on the InP-based Type I material is limited to around 2.3 μm [15]. Recently, we demonstrated 2.3x μm heterogeneous III-Von-silicon distributed feedback (DFB) laser sources based on an InP-based Type II heteros...

Mid-infrared integrated photonics on silicon: a perspective

“…We expect that similar designs can be implemented to allow wavelength tuning of heterogeneously integrated mid-IR lasers across the gain bandwidth of the lasing medium. The same group also recently demonstrated a multiwavelength DFB laser array on Si covering 2.28-2.43 μm, where the lasers are all fabricated from one bonded III-V die with their wavelengths controlled by SOI grating pitch [82].…”

Widely Tunable III–V/Silicon Lasers for Spectroscopy in the Short-Wave Infrared

“…Therefore, a broad wavelength coverage III-V-on-silicon DFB laser array with wavelength spacing around 6 nm can be used to detect any absorption features of molecules in this spectral range. Compared with our previously demonstrated heterogeneously integrated InP-based type-II DFB laser [32]- [33], the device shown here can operate in CW at room temperature and above without mode-hopping.…”

“…We have demonstrated III-V-on-silicon DFB laser arrays with wavelength spacing of 30 nm at 2.35 μm wavelength range [33]. In order to achieve complete spectral coverage, in this paper we report a heterogeneously integrated InP-based type-II DFB laser array with a wavelength spacing of 6 nm (combined with the wavelength tuning discussed above).…”

III-V/silicon photonic integrated circuits for spectroscopic sensing in the 2um wavelength range

“…The lasing wavelength of the III-V-on-silicon DFB lasers is determined by the silicon grating pitch. Figure 6(b) shows the emission spectra of six 1000 µm-long heterogeneously integrated DFB lasers in an array [18]. As the silicon grating pitch increases from 343 nm to 368 nm, the lasing wavelength shifts from 2280 nm to 2430 nm.…”

“…Silicon is an indirect bandgap semiconductor with extremely low light emission efficiency, transparent beyond 1.1 µm wavelength. In order to realize fully integrated silicon photonic systems for the 2 µm wavelength range, a lot of effort has been devoted to integrate 2 µm-wavelength-range active photonic devices on silicon [11][12][13][14][15][16][17][18][19][20]. In this contribution, we present the development of fully integrated III-V-on-silicon photonic circuits for spectroscopic sensing applications in the 2µm wavelength range.…”