Q-peak has demonstrated a compact, pulsed eyesafe laser architecture operating with >10 mJ pulse energies at repetition rates as high as 160 Hz. The design leverages an end-pumped solid-state laser geometry to produce adequate eyesafe beam quality (M2∼4), while also providing a path toward higher-density laser architectures for pulsed eyesafe applications. The baseline discussed in this paper has shown a unique capability for high-pulse repetition rates in a compact package, and offers additional potential for power scaling based on birefringence compensation. The laser consists of an actively Q-switched oscillator cavity producing pulse widths <30 ns, and utilizing an end-pumped Nd:YAG gain medium with a rubidium titanyl phosphate electro-optical crystal. The oscillator provides an effective front-end-seed for an optical parametric oscillator (OPO), which utilizes potassium titanyl arsenate in a linear OPO geometry. This laser efficiently operates in the eyesafe band, and has been designed to fit within a volume of 3760 cm3. We will discuss details of the optical system design, modeled thermal effects and stress-induced birefringence, as well as experimental advantages of the end-pumped laser geometry, along with proposed paths to higher eyesafe pulse energies.
Q-Peak has demonstrated a novel, compact, pulsed eyesafe laser architecture operating with <10 mJ pulse energies at repetition rates as high as 160 Hz. The design leverages an end-pumped solid-state laser geometry to produce adequate eyesafe beam quality (M2 ~4), while also providing a path towards higher-density laser architectures for pulsed eyesafe applications. The baseline discussed in this paper has shown a unique capability for high pulse repetition rates in a compact package, and offers additional potential for power scaling based on birefringence compensation. The laser consists of an actively Q-switched oscillator cavity producing pulse-widths <30 ns, and utilizing an end-pumped Nd: YAG gain medium with a Rubidium Titanyl Phosphate (RTP) electro-optical crystal. The oscillator provides an effective front-end-seed for an optical parametric oscillator (OPO), which utilizes Potassium Titanyl Arsenate (KTA) in a linear OPO geometry. This laser efficiently operates in the eyesafe band, and has been designed to fit within a volume of 3760 cm3. We will discuss details of the optical system design, modeled thermal effects and stress-induced birefringence, as well as experimental advantages of the end-pumped laser geometry, along with proposed paths to higher eyesafe pulse energies.
After successfully bonding VCSEL arrays to GaAs dummy chips and CMOS chips with three different bonding techniques, the thermal resistance and crosstalk of the bonded VCSEL arrays were measured. The thermal resistance of the VCSELs bonded to a GaAs substrate was found to be as low as 1100 K/W, indicating a high quality contact. Less than 100 K/W thermal crosstalk was also observed in the VCSEL arrays with a pitch of 250 micrometers . The thermal resistance of the VCSEL bonded to a CMOS chip with a standard bonding pad design has also been measured, which is 2490 K/W. The high thermal resistance is due to the dielectric layers underneath the bonding pads.
The fabrication technologies and bonding characteristics of three VCSEL bonding techniques are compared in order to determine the more reliable and robust.
We presented here the design and initial demonstration of three optoelectronic database filters. Each of these systems is intended to serve as an interface between a page oriented optical storage devices and an electronic host computer. In addition to providing optical/electrical data conversion, each filter is capable of reducing the high data rate optical input to low data rate electronic signals compatible with conventional database management systems. For each filter, the system objectives and associated design trade offs are presented. Finally, an overall trend towards increasing pixel logic complexity while reducing optical system complexity is discussed.
This paper presents the construction of the smart pixel arrays which perform AND and XOR functions with three-input and one-output optical signals for the application of an optical database filter. The device is based on oxide confined VCSELs bump bonded to GaAs MESFET pixels. The MSM photodetectors are monolithically integrated with MESFETs.
Integration of vertical cavity surface emitting lasers (VCSELs) onto a prefabricated smart pixel chip introduces fabrication problems since they can not be grown on foundry fabricated Si CMOS or GaAs MESFET circuit. This paper presents an approach to flip-chip bump-bonding VCSEL-arrays to a pixel chip in which each VCSEL is bonding directly to the appropriate pixel circuit. Thus, no added area is required and the interconnect capacitance is held to a minimum. The technique requires contacting both the n- and p-mirror of the VCSEL on the same side of the VCSEL chip and in the same plane. This allows bump bonding both contacts to the pixel chip and subsequent removal of the VCSEL chip substrate. The steps required to accomplish the VCSEL coplanar bonding include reactive ion etching of mesas and device separation in BCL3/Cl, electroplating a 4.5 micrometers high gold coplanar contact post, In/Sn alloy solder deposition, bonding to the smart pixel chip, and accurate alignment of the VCSEL and pixel chips, epoxy underfill and at last substrate removal.
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