High-efficiency intracavity Nd:YVO4\KTA optical parametric oscillator with 3.6 W output power at 1.53 microm

High-performance Kerr microresonator optical parametric oscillator on a silicon chip

Optical parametric oscillation (OPO) is distinguished by its wavelength access, that is, the ability to flexibly generate coherent light at wavelengths that are dramatically different from the pump laser, and in principle bounded solely by energy conservation between the input pump field and the output signal/idler fields. As society adopts advanced tools in quantum information science, metrology, and sensing, microchip OPO may provide an important path for accessing relevant wavelengths. However, a practical source of coherent light should additionally have high conversion efficiency and high output power. Here, we demonstrate a silicon photonics OPO device with unprecedented performance. Our OPO device, based on the third-order (χ⁽³⁾) nonlinearity in a silicon nitride microresonator, produces output signal and idler fields widely separated from each other in frequency ( > 150 THz), and exhibits a pump-to-idler conversion efficiency up to 29 % with a corresponding output idler power of > 18 mW on-chip. This performance is achieved by suppressing competitive processes and by strongly overcoupling the output light. This methodology can be readily applied to existing silicon photonics platforms with heterogeneously-integrated pump lasers, enabling flexible coherent light generation across a broad range of wavelengths with high output power and efficiency.

Efficient 1.7 μm light source based on KTA-OPO derived by Nd:YVO4 self-Raman laser

An intra-cavity optical parametric oscillator (OPO) emitting at 1.7 μm derived by Nd:YVO₄ self-Raman laser is demonstrated in this Letter, with a KTiOAsO₄ (KTA) crystal used as nonlinear optical crystal. A laser diode end-pumped acousto-optic Q-switched Nd:YVO₄ self-Raman laser at 1176 nm was employed as the pump source. At an incident pump power of 12.1 W and a pulse repetition frequency of 60 kHz, average output power up to 1.2 W signal light at 1742 nm was obtained, with diode-to-signal conversion efficiency of 10%. The pulse width was about 11 ns and spectral line width was less than 0.5 nm for the signal light. The results show that compact intra-cavity KTA-OPO derived by Nd:YVO₄ self-Raman laser is an efficient method for 1.7 μm waveband laser generation, with potential applications in biological imaging, laser therapy, special materials processing, etc.

Compact self-cascaded KTA-OPO for 2.6 μm laser generation

We reported a compact self-cascaded KTA-OPO source for 2.6 μm coherent light generation. The OPO is driven in a diode end-pumped and Q-switched Nd:YVO₄ laser cavity. Two OPO processes occurred in the same KTA crystal with non-critical phase matching. At an incident diode pump power of 8.7 W and a pulse repetition frequency of 60 kHz, the OPO can generate a maximum average output power of 445 mW at 2.59 μm. The slope efficiency was about 12.7%, and the power fluctuation was less than 8%. Therefore, the self-cascade OPO based on KTA offers a promise scheme for the rugged and compact mid-infrared 2.6 μm laser generation.

Efficient RTP-based OPO intracavity pumped by an acousto-optic Q-switched Nd:YVO₄ laser

This Letter describes an intracavity pumped optical parametric oscillator (OPO) based on noncritical phase matching RbTiOPO4 (RTP) crystal driven by a laser diode end-pumping acousto-optic Q-switched Nd:YVO4 laser. Simultaneous efficient signal light at 1.6 μm and idler light at 3.1 μm outputs were obtained. At an incident pump power of 10.5 W and a Q-switching pulse repetition frequency of 60 kHz, 1.42 W at center wavelength of about 1619 nm and 0.38 W at 3108 nm were achieved, with the diode to OPO total output conversion efficiency up to 17.1%. The pulse width is about 6.5 ns for the signal light corresponding to the fundamental light at 1064 nm of about 10 ns. The spectral widths of the signal and idler light are narrower than 0.5 and 1.0 nm. The result shows that the RTP crystal is an efficient crystal to generate eye-safe and mid-infrared lights by making full use of noncritical phase matching.

Laser operation of diode-pumped Er,Yb co-doped YAG ceramics at 1.6 μm

1.6 μm eye-safe emission of a diode pumped Er,Yb co-doped YAG ceramic laser is firstly demonstrated. Operation of the ceramic laser under different ceramic sample lengths, co-doping concentrations and control temperatures were experimentally investigated. A maximum output power of 222 mW was achieved at an absorbed pump power of 8.1 W, corresponding to a conversion efficiency of 2.74%. Laser emission at 1.05 μm for transition of the Yb(3+) ions was also studied on the same ceramic samples. The results clearly show the existence of resonantly energy transfer from the Yb(3+) ions to Er(3+) ions.

Nanosecond nonlinear Čerenkov conical beams generation by intracavity sum frequency mixing in KTiOAsO4 crystal

Nanosecond Čerenkov-type conical beam at 628 nm is obtained by intracavity sum frequency mixing (SFM) of 1064 and 1534 nm in KTiOAsO(4) (KTA) crystal. The 1534 nm signal generated by the KTA optical parametric oscillation (OPO), respectively, interacts with the orthogonally polarized 1064 nm radiations by the nonlinear Čerenkov SFM, emitting two red rings with cone angles of 11.4° and 16.0°, respectively. Multidomain structure observed in the KTA crystal can account for the corresponding phenomenon. The KTA crystal simultaneously serves as OPO medium and Čerenkov radiation emitter in this experiment, indicating that it is a promising multifunctional nonlinear crystal material. Furthermore, the naturally grown crystal combined with intracavity Čerenkov-type configuration will provide a simple and compact approach, opening a door for the wide application of nonlinear Čerenkov radiation sources due to its cost-effectiveness.

Theoretical and experimental studies on output characteristics of an intracavity KTA OPO

An acousto-optically Q-switched Nd:YVO(4)/KTiOAsO(4) (KTA) intracavity optical parametric oscillator (OPO) is efficiently realized in singly resonated scheme. With an end-pumping diode power of 25.9 W, output signal (1535 nm) power of 3.77 W and idler power (3467 nm) of 1.18 W are obtained at a pulse repetition rate of 50 kHz. A rate-equation model is set up to simulate the output power and time characteristics of both signal and idler waves. And both the numerical and experimental results show that the idler pulse width is shorter than the signal one in a singly resonant OPO.