Grating-coupled Surface-emitting Laser Research Articles

Polarization-stable single-mode 795 nm grating-coupled surface-emitting laser for quantum sensing

We demonstrate a polarization-stable and single-mode grating-coupled surface-emitting laser (GCSEL) with high side-mode suppression ratio (SMSR) of ∼40 dB and orthogonal polarization suppression ratio (OPSR) of ∼25 dB around 795 nm. The fabricated devices have low threshold current of ∼4.8 mA and low electrical resistance of 53 Ω at 25 °C. Meanwhile, a low thermal resistance of ∼1 K/mW is achieved, which is comparable with that of the record of ever reported for vertical-cavity surface-emitting lasers (VCSELs). The far-field divergence angle of surface-emitting beam is ∼14.5°x14.7° at an injection current of 12 mA indicating a relatively good beam quality. Our results open what we believe is a new way to produce polarization-stable single-mode surface-emitting lasers with simple fabrication process. While the GCSEL is specifically designed for quantum sensing applications such as atomic clocks, magnetometers, and gyroscope, its performance in terms of low-power consumption, low thermal resistance, good beam qualities, and wafer-level testing are of particular interest for a wide range of applications.

Blue Light Source Based on a ppKTP SHG Using a Grating-Coupled Laser Diode

In this letter, we present the first experimental results of a single-pass second-harmonic (SH) generation from a grating-coupled surface-emitting laser (GCSEL) with integrated dual-grating reflector. In pulse operation, the maximum SH peak power was obtained at 0.66 W, yielding a normalized conversion efficiency of 0.6times10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . A high-level monolithical integration of the GCSEL device led to a compact blue light source, which was based on a frequency-doubled near-IR laser diode.

Picosecond pulse generation using a saturable absorber section of grating-coupled surface-emitting laser

We report on a passively and hybridly mode-locked grating-coupled surface-emitting laser (GCSEL) using the unpumped section of the GCSEL as a saturable absorber. We obtain 8.8-ps full-width at half-maximum (FWHM) autocorrelation pulses in passive mode-locked operation and an FWHM pulse duration of 3.4 ps in hybrid mode-locked operation, which are the shortest pulses from a GCSEL external cavity. With hybrid mode-locking, a peak power of 0.26 W and a spectral bandwidth of 0.6 nm are obtained. These results demonstrate the potential of multisegment GCSELs in ultrashort pulse generation.

External-cavity, actively mode-locked grating-coupled surface-emitting laser and amplification characteristics of a grating-coupled semiconductor optical amplifier.

An external-cavity, actively mode-locked grating-coupled surface-emitting semiconductor laser (GCSEL) is demonstrated for the first time to the authors' knowledge. The mode-locked oscillator generates a train of optical pulses at a 297-MHz pulse-repetition frequency. The optical pulse from the oscillator has a width of 22.6 ps and a spectral bandwidth of 0.07 nm at 975.9 nm, giving a time-bandwidth product of 0.50. In addition, amplification characteristics of a grating-coupled semiconductor optical amplifier are studied with a continuous-wave external-cavity GCSEL.

Amplified spontaneous emission and threshold crossing in a distributed-Bragg reflector grating-coupled surface-emitting laser

The threshold crossing inside a second-order distributed-Bragg reflector grating-coupled surface-emitting laser is theoretically investigated. The spontaneous emission field, looked upon as the driving source of the laser radiation, is described in a semi-classical way in the spectral domain. The gain, the source and possibly the refractive index, are saturated through amplified spontaneous emission, integrated over the whole spectral range of the main longitudinal mode. Simple expressions are obtained for both the laser intensity and linewidth as a function of the pump, which remain continuously valid across the threshold.

Grating-coupled surface-emitting laser with a hyperbolic unstable resonator producing a stable focused output beam

A grating-coupled surface-emitting semiconductor laser has been integrated with a focusing diffractive beamforming element. A hyperbolic unstable resonator is used to introduce mode discrimination and suppress filamentation in a broad geometry, resulting in a 200-μm-wide coherent output. The light is focused 500 μm above the laser surface to a spot size of 5×7 μm. A remarkable beam stability is observed with very small spot size variation and beam-steering up to three times the threshold current under continuous operation.

Broad tunability of grating coupled surface-emitting laser with external cavity

The wavelength-tuning properties of an InGaAs grating-coupled surface-emitting laser (GCSEL) are presented. Wide, continuous tunable laser oscillation has been observed over a range of 115 nm, between 900 nm–1015 nm, under pulsed current excitation. Different external cavities have been studied to achieve optimal performance.

Optical field analysis of a circular grating-coupled surface-emitting laser with integrated focusing outcoupler

The lasing characteristics of a circular grating-coupled surface-emitting laser (GCSEL) with an integrated focusing outcoupler are investigated. Measured near and far fields suggest lasing in two near orthogonal and mutually incoherent linear elements, rather than ideal circular modes of the planar circular resonator, resulting in a degradation of the focused spot quality. Modeling of the evolution of the emitted optical field by Fresnel diffraction calculations, using a new orthogonal projection scheme to account for polarization, supports this assumption. Using the theory, we have also estimated the degradation of the focused spot quality induced by random errors in the period of the focusing outcoupler caused by the limited resolution of the electron-beam lithography system used to fabricate the device. We found this effect to be small compared to the effect of the nonideal mode characteristics.

Very low threshold 1.55 μm grating coupled surface-emitting lasers for optical signal processing and interconnect

We report in this work a record low threshold (∼4 mA, cw), 1.55 μm wavelength, grating-coupled surface-emitting laser (GCSEL) which rivals all other existing SELs in the 1.3 or/and 1.55 μm regions. Methods to improve the asymmetric far-field patterns and to obtain even lower threshold SELs are also demonstrated and/or suggested.

Design and performance of a low-threshold-current grating-coupled surface-emitting laser

The design and performance of a low-threshold-current grating-coupled surface-emitting (GSE) strained-InGaAs single-quantum-well laser with a distributed Bragg reflector has been demonstrated. By considering the field discontinuity at the gain/grating section interface and the actual fabrication process, our calculations show that the GaAs optical confinement structure can be the best candidate for providing high effective reflectivity in the grating section. At room temperature, the GSE laser shows a continuous-wave threshold current as small as 15 mA and a beam divergent angle of 10° × 0.59°.

Low threshold current grating-coupled surface-emitting strained-InGaAs single quantum well laser with GaAs optical confinement structure

We have demonstrated low threshold current operation of a grating-coupled surface-emitting strained-InGaAs single quantum well laser with a distributed Bragg reflector. By considering the field discontinuity at the gain/grating section interface, our calculations show that the GaAs optical confinement structure can provide high effective reflectivity in the grating section. As a result, continuous wave threshold currents as small as 15 mA were attained at 22 °C, which is the lowest threshold current reported for a grating-coupled surface-emitting laser fabricated without epitaxial regrowth.

Two dimensional grating surface emitting laser arrays with wide lateral extent

Two dimensional grating-coupled surface-emitting laser arrays with as many as 250 ridge-guided elements in each gain section were fabricated. Four gain sections were operated simultaneously with a resulting aperture of 1.0*2.1 mm/sup 2/.

High-power, 4 W pulsed, grating-coupled surface-emitting laser

Surface-emitting lasers fabricated with second-order grating, distributed Bragg reflector regions for output coupling and feedback are demonstrated to operate at high output powers. Powers of 1.75 and 4 W pulsed are reported for single gain section and three gain section lasers.