Alexei Sirbu

Long-wavelength VCSELs: Power-efficient answer

The commercialization of long-wavelength vertical-cavity surface-emitting lasers (VCSELs) is gaining new momentum as the telecoms market shifts from long-haul applications to local and access networks. These small, power-efficient devices offer several advantages over traditional edge-emitters.

2.6 W optically-pumped semiconductor disk laser operating at 1.57-µm using wafer fusion

We report a wafer fused high power optically pumped semiconductor disk laser incorporating InP-based active medium fused to a GaAs/AlGaAs distributed Bragg reflector. A record value of over 2.6 W of output power in a spectral range around 1.57 microm was demonstrated, revealing the essential advantage of the wafer fusing technique over monolithically-grown all-InP-based structures. The presented approach allows for integration of lattice-mismatched compounds, quantum-well and quantum-dot based media. This would provide convenient means for extending the wavelength range of semiconductor disk lasers.

Broadband MEMS-Tunable High-Index-Contrast Subwavelength Grating Long-Wavelength VCSEL

A widely-tunable single-mode 1.3 μm vertical-cavity surface-emitting laser structure incorporating a microelectromechanical system-tunable high-index-contrast subwavelength grating (HCG) mirror is suggested and numerically investigated. A linear tuning range of 100 nm and a wavelength tuning efficiency of 0.203 are predicted. The large tuning range and efficiency are attributed to the incorporation of the tuning air gap as part of the optical cavity and to the use of a short cavity structure. The short cavity length can be achieved by employing a HCG design of which the reflection mechanism does not rely on resonant coupling. The absence of resonance coupling leads to a 0.59 λ-thick penetration depth of the HCG and enables to use a 0.25 λ-thick tuning air gap underneath the HCG. This considerably reduces the effective cavity length, leading to larger tuning range and efficiency. The basic properties of this new structure are analyzed, and shown to be explained by analytical expressions that are derived in the paper. In this context, the penetration depth of the HCG is introduced and shown to be an important characteristic length scale. Throughout the tuning wavelength range, strong single mode operation was maintained and uniform output power is expected.

1.3-µm optically-pumped semiconductor disk laser by wafer fusion

We report a wafer-fused high power optically-pumped semiconductor disk laser operating at 1.3 µm. An InP-based active medium was fused with a GaAs/AlGaAs distributed Bragg reflector, resulting in an integrated monolithic gain mirror. Over 2.7 W of output power, obtained at temperature of 15 °C, represents the best achievement reported to date for this type of lasers. The results reveal an essential advantage of the wafer fusing technique over both monolithically grown AlGaInAs/GaInAsP- and GaInNAs-based structures.

3 W of 650 nm red emission by frequency doubling of wafer-fused semiconductor disk laser

3 W at genuine red wavelength of 650 nm has been achieved from a semiconductor disk laser by frequency doubling. An InP based active medium was fused with a GaAs/AlGaAs distributed Bragg reflector resulting in an integrated monolithic gain mirror. 6.6 W of output power at the fundamental wavelength of 1.3 µm represents the best achievement reported to date for this type of lasers.

1.38-µm mode-locked Raman fiber laser pumped by semiconductor disk laser

A mode-locked Raman fiber laser pumped by 1.3 µm semiconductor disk laser is demonstrated. Direct Watt-level core-pumping of the single-mode fiber Raman lasers and amplifiers with low-noise disk lasers is demonstrated to represent a highly practical solution as compared with conventional scheme using pumping by Raman wavelength convertors. Raman laser employing passive mode-locking by nonlinear polarization evolution in normal dispersion regime produces stable pedestal-free 1.97 ps pulses at 1.38 µm. Using semiconductor disk lasers capable of producing high power with diffraction-limited beam allows Raman gain to be obtained at virtually any wavelength of interest owing to spectral versatility of semiconductor gain materials and wafer-fusing technology.

8 mW fundamental mode output of wafer-fused VCSELs emitting in the 1550-nm band

Record fundamental mode output power of 8mW at 0°C and 6.5mW at room temperature is achieved with wafer-fused VCSELs incorporating regrown tunnel junction and emitting at the 1550nm waveband.

Raman fiber laser pumped by a semiconductor disk laser and mode locked by a semiconductor saturable absorber mirror

A 1.6µm mode-locked Raman fiber laser pumped by a 1480nm semiconductor disk laser is demonstrated. Watt-level core pumping of the single-mode fiber Raman lasers with low-noise disk lasers together with semiconductor saturable absorber mirror mode locking represents a highly practical solution for short-pulse operation.

10-Gb/s and 10-km error-free transmission up to 100°C with 1.3-μm wavelength wafer-fused VCSELs

10-Gb/s modulation speed and transmission over 10-km SM fiber with BER < 10−11 up to 100°C temperature are achieved with optimized wafer-fused GaAs/AlGaAs-InP/InAlGaAs VCSELs incorporating re-grown tunnel junction. These VCSELs operate in the 1310-nm waveband and emit more than 1-mW single mode power in the full temperature range.

Wafer-fused heterostructures: application to vertical cavity surface-emitting lasers emitting in the 1310 nm band

Currently, wafer-fusion technology represents an effective technique for enhancing the performance of long-wavelength vertical cavity surface-emitting lasers (VCSELs) based on classical double heterostructures with multi-quantum well active regions. Using the example of 1310 nm wavelength VCSELs, we demonstrate the status of this technology for wafer-level scale, wavelength-controlled devices with high performance, capable of operation in a wide temperature range up to 90 °C with single-mode output power levels in excess of 1 mW and a side mode suppression ratio (SMSR) in excess of 40 dB. No degradation was observed in a qualification lot that operated at 10 mA and 90 °C for 2000 h.