619 nm Fiber Laser 

Sum-Frequency Generation (SFG)

The wavelength range of QTekLaser^TM products can be further extended using the nonlinear process of sum-frequency generation (SFG). This architecture is illustrated in figure 2. The two fundamental lasers are usually made of different gain fiber amplifiers. The extended wavelength values are summarized in the blue-shaded cells of table 1. This method achieves high power at certain wavelengths.

Specifications

Wavelength	619 nm
Output power	1-100 mW
Operation Mode	CW
Polarization Extinction Ratio (PER)	18 dB
Polarization direction	Slow axis
Power stability	<1%
Laser linewidth	<200 kHz
Frequency modulation (FM) gain	500 (-323) uA/V (MHz/V)
FM bandwidth	DC-10 MHz
FM input impedance	50 Ohm
FM input range	+/- 1.3 V
Operating temperature	16-24 °C
Cooling mode	Air cooling
Beam quality	TEM00, M2~1.0
Output fiber type	PM630
Output fiber connector	FC/APC
Output fiber length	2 m
Relative Intensity Noise (RIN)	-125 dBc/Hz >10kHz
Side-Mode Supression Ratio (SMSR)	58 dB
Chassis	3U 19" Rack mount

QTekLaser^TM lasers comply with Federal Regulations (21 CFR Subchapter J, Part 1040)  as administered by the Center for Devices and Radiological Health and are certified to IEC 60825-1:2014 standards.

It is the end user's responsibility to ensure that no significant light is retroreflected back into QTekLaser^TM systems as this can degrade performance and potentially damage the lasers. To prevent this, the use of an external optical isolator is strongly recommended.  Damage due to retroreflected light is not covered under warranty.

Ordering Information

Performance

Beam Profile

Figure 3. Beam Profile 619 nm

Optical Spectrum

Figure 4. Optical Spectrum 619 nm SMSR 59 dB

Relative Intensity Noise (RIN)

Figure 5. Relative Intensity Noise (RIN) 619 nm -125 dBc/Hz >10kHz

Laser Power vs. Current

Figure 6. Laser Power vs. Current 619 nm

Tunability
Frequency vs. Seed Laser Temp.

Figure 7. Tunability: Frequency vs. Seed Laser Temp. 619 nm fiber laser

Tunability
Wavelength vs. Seed Laser Temp.

Figure 8. Tunability: Wavelength vs. Seed Laser Temp. 619 nm

Tunability
Frequency vs. Seed Laser Current

Figure 9. Tunability: Frequency vs. Seed Laser Current 619 nm

Tunability
Wavelength vs. Seed Laser Current

Figure 10. Tunability: Wavelength vs. Seed Laser Current 619 nm

Optimal SFG temperature vs. Wavelength

Figure 11. Optimal SFG temperature vs. Wavelength 619 nm

Frequency Modulation via the SMA port

Figure 12. Frequency Modulation via the SMA port 619 nm

Quantum Networking

Quantum networks rely on exquisitely controlled, low-noise optical signals to transmit quantum states (e.g. single photons, entangled photons) over fibers or free-space links. The 619 nm fiber laser from QTekLaser™ offers a compelling light-source solution for quantum networking platforms that exploit visible-wavelength transitions (for instance, in certain quantum memories, frequency converters, or quantum repeaters).

Key Benefits in Quantum Networking

• High coherence and narrow linewidth — With a linewidth below 200 kHz, the 619 nm output supports long coherence times and low phase noise, critical for maintaining quantum phase relationships and ensuring high-visibility interference between remote nodes.
• Low relative intensity noise (RIN) — The design delivers RIN better than –125 dBc/Hz (above 10 kHz), which helps suppress amplitude fluctuations     that would otherwise degrade quantum bit error rates.
• Power stability & reliability — The system offers <1% power variation over time, enabling stable link budgets and predictable behavior in long-duration experiments.
• Fiber-coupled polarization-maintaining (PM) output —The PM630 fiber output with FC/APC connector ensures polarization purity and easy fiber integration, which is important for polarization-encoded qubits or coupling into downstream optics.
• Compact, rack-mount form with IoT control — In a 3U, 19″ chassis with forced-air cooling, and integrated IoT-enabled interface, the laser is well suited for deployment in laboratory racks or quantum network nodes.
• Sum-frequency generation (SFG) architecture — By internally converting from two seed lasers via SFG, the laser can deliver a stable visible wavelength without requiring external non-linear modules, simplifying system assembly and reducing alignment sensitivity.

Use Cases & Scenarios

• Frequency conversion / quantum transduction — In many quantum networks, one needs to convert photons between telecom bands and visible or near-visible wavelengths (for atomic or solid-state quantum memories). The 619 nm source can serve as a pump or intermediate wavelength in     sum-/difference-frequency conversion modules.
• Quantum memory addressing / readout — Some quantum memory media (e.g. SnV) have transitions near 619 nm; the laser can be used to address, excite, or read out states in these systems.
• Inter-node synchronization / calibration — The laser may be used to generate reference or calibration signals among nodes, enabling phase locking,     channel stabilization, or alignment verification.
• Interferometric quantum protocols — In quantum key distribution (QKD) or entanglement distribution over interferometers, the high coherence and low noise characteristics support high visibility and low decoherence.

Spec Highlights for Quantum Networking Applications

Mechanical Dimensions

Product Photographs